3 THE PLANT KINGDOM
CHAPTER NO.3 THE PLANT KINGDOM
A16
INTRODUCTION
ALGAE:Algae
are non- vascular, photosynthetic aquatics, form accessory spores for asexual
reproduction.Unicellular or multicellular, non- jacketed sex organs for sexual
reproduction,in which embryo stage is absent.Algae exist in environments
ranging from oceans, rivers, and lakes to ponds,brackish waters and even
snow.Algae are usually green, but they can be found in a variety of different
colors.For instance, algae living in snow contain carotenoid pigments in
addition to chlorophyll, hence giving the surrounding snow a distinctive red
hue.
In other words Algae is a simple, non- flowering and
typically aquatic plant that includes seaweeds and many single celled forms.
CHARACTERISTICS OF ALGAE:
1. They are unicellular or multicellular.
2. They contain chlorophyll.
3. They are autotrophic.
3. Vascular tissue absent.
4. Unlike traditional plants algae do not have true
roots, stems and leaves.Hence they need to be near a moist or watery
environment dsurvive. In other words they do not possess vascular tissue
necessary for conduction of water and minerals.
5. The sex organs are unicellular or multicellular.
6. Reproduction in algae occurs in both asexual and
sexual forms.
7. They are aquatic or semi-aquatic.
8. Photosynthetic pigments Chlorophyll a ,Carotenes
and Xanthophyll occur in all algae.
9. Some additional photosynthetic pigments are
present in every algal group.On the basis of PIGMENTS algae are divided into
three major groups;
a) Brown algae: contains Fucoxanthin and Chlorophyll
c.
b) Red algae: contains Phycobilins
c) Green algae: contains Beta carotene and
Chlorophyll b.
10. Algae contains near about 18,000 genera with
29,000 species.
11. All of them being a thallus, lack a
differentiation of body in true roots,stem and leaves.
MAJOR DIVISIONS OF ALGAE:
The three major divisions of algae are:-
1) RHODOPHYTA:-
RED ALGAE
Examples: - Grinellia, Porphyra
2) PHAEOPHYTA:- BROWN ALGAE
Examples:- Sargassum, Laminaria, Sargassum
3) CHLOROPHYTA
:- GREEN ALGAE
Examples:- Spirogyra, Chalamydomonas
ECONOMIC IMPORTANCE OF ALGAE
Algae have diverse economic uses:
1)ALGAE AS A FOOD-_Algae
constitutes an important source of food for the fishes and other aquatic
animals, mammals and other animals including man directly or indirectly.
Example;- Chlorella, Ulva, Nostoc etc.
2)ALGAE IN MEDICINE-
Some algae yield antibacterial substances effective against a number of gram-
positive and gram-negative bacteria . Example:-Chlorellin is the first
antibiotic obtained from Chlorella in 1944. Corallina algae are used in
treating worminfections.
3) COMMERCIAL IMPORTANCE:
Agar is used in the preparation of jelliesand ice-cream. It is obtained from
Gelidium and Gracilaria. Carrageenin is used as an emulsifier in chocolates,
paints, and toothpaste. It is obtained from the red algae.
4) They perform half of the total CARBON
DIOXIDE-FIXATION on earth by
photosynthesis, acting as the primary producers in
aquatic habitats.
LET US KNOW, WHAT WE HAVE LEARNT!
PART- A- SHORT ANSWER TYPE QUESTIONS:
a) MULTIPLE CHOICE QUESTIONS:-—
Q1.An algae which
can be employed for food for human being is:
a) Ulothrix
b) Chlorella
b) Spirogyra
d) Polysiphonia
Q2. Which one of
the Following is a, red algae:
a) Gelidium
b) Chlorella
c) Volvox
d) Ulothrix.
Q3. Algae
consists of nearly:
a) 18,000 genera with 29000 species
b)29,000 genera with 18,000 species
c) 16,000 genera with29000 species
d) 18,000 genera with 19000 species
Q4. An Example of
colonial algae is:
a) Volvox
b) Ulothrix
c)Spirogyra
d) Chlorella
Q5. Carrageenin
is used as:
a) an emulsifier in chocolates
b) an emulsifier in paints
C) an emulsifier in toothpaste
d) All of the above
b) TRUE/FALSE:-—
Q1. Vascular tissue is present in algae.
Q2. Only asexual reproduction occurs in algae.
Q3. Algae do carbon dioxide-fixation on earth by
photosynthesis.
c) FILL IN THE BLANKS:
Q.1---------—---algae are used in treating worm
infections.
Q.2 Porphra is a-----------—algae.
ANSWER KEY: PART A
a) MCQ's.--
Ans 1. b - Chlorella
Ans 2. a - Gelidium
Ans 3. a - 18,000 genera with 29000 species
Ans 4.a - Volvox
Ans 5. d - All of the above.
b) TRUE/FALSE :—
Ans 1.False (Vascular tissue absent)
Ans 2.False (Reproduction in algae occurs in both
asexual and sexual forms)
Ans 3.True
c} FILL IN THE BLANKS:--
Ans 1. Corallina
Ans 2. Brown algae.
PART B : SHORT ANSWER TYPE QUESTIONS:
Q1 What do you mean by Algae?
Q2. Give major division of Algae?
Q3. How are algae different from traditional plants?
PART C: LONG ANSWER TYPE QUESTIONS:
Q1. State the general characteristics of Algae.
Q2. Explain the economic importance of Algae.
A17
INTRODUCTION:Students,
as you have studied in the previous assignment that there are three main types
of algae: 1. Red algae 2.Green algae 3.BrownAlgae Do you think why it is so?
Yes, it is due to the presence of different types of PIGMENTS present in algae.
Let us study in detail about different types of algae.
1.RED ALGAE (RHODOPHYCEAE):
Rhodophyceae
are commonly called red algae because of the predominance of the red pigment,
r-phycoerythrin in their body.The red thalli of most of the red algae are
multicellular. The food is stored as floridean starch.The red algae usually
reproduce vegetatively by fragmentation,reproduceasexually by non-motile
spores, and sexually by non-motile gametes.The common members are:
Polysiphonia, Porphyra, Gracilaria and Gelidium.
GREEN ALGAE (CHLOROPHYCEAE):
They
are usually grass green due to the dominance of pigments chlorophyll a and
b.Most of the members have one or more storage bodies called pyrenoids located
in the chloroplasts, which contain protein besides starch. Green algae usually
have a rigid cell wall made of an inner layer of cellulose and anouter layer of
pectose.Vegetative reproduction usually takes place by fragmentation or by
different types of spores, asexual reproduction is by flagellated zoospores
produced in zoosporangia, and the sexual reproduction by the formation of sex
cells and it may be isogamous, anisogamous or oogamous.Some commonly found
green algae are:
Chlamydomonas, Volvox, Ulothrix, Spirogyra and
Chara.
BROWN ALGAE (PHAEOPHYCEAE):
LET US KNOW WHAT WE HAVE LEARNT !
PART-A SHORT ANSWER TYPE QUESTIONS
a) MCQs:
Q1. All algae
possess:
a) Nuclei
b) Chloroplasts
c) Both ‘a’ & ‘b’
d) None of these
Q2. Both
Chlorophyll ‘a’ and d’ Present in
a) Rhodophyceae
b) Phaeophyceae
c) Chlorophyceae
d) None of these
Q3. External
fertilisation occurs in majority of
a) Algae
b) Fungi
c) Liverworts
d) Mosses
Q4. Red Algae
differ from Green Algae and Brown Algae in Having
a) No chlorophyll ‘a’
b) No Differentiated Cells
c) No flagellated stage in their life cycle
d) Haemoglobin with in their cells
Q5. Algae are
found in all of the following places except:
a) oceans
b) Soils
c) Lakes And Streams
d) Association with fungi
b) TRUE / FALSE:
Q1. Red algae occur in marine water.
Q2. Green algae usually have a rigid cell wall made
of an inner layer of pectose and an outerlayer of cellulose.
Q3. Algae are autotrophs.
c) FILLIN THE BLANKS:
Q1.Brown Algae Contain dominating pigment —--.
Q2. Green Algae are considered---------- of all
terrestrial plants.
ANSWER KEY- PART-A
a) MCQs:
1. c nuclei and chloroplasts
2. a rhodophyceae
3. a algae
4. c no flagellated stage.
5. c lakes and streams
b) TRUE/ FALSE:
1. TRUE (Red Algae due to the nature of their
pigments and their light absorbing capacity are able togrow in depth of sea.)
2. FALSE (Green algae usually have a rigid cell wall
made of an inner layer of cellulose and an outer layer ofpectose.)
3. TRUE (Algae create their own nutrients and
Energy.)
c) FILL IN THE BLANKS:
1. Fucoxanthin
2. Ancestors
PART-B SHORT ANSWER TYPE QUESTIONS
Q1. Differentiate between Red algae and Brown algae.
Q2. What is basis of classification of algae?
Q3.Write short note on green Algae.
PART-C LONG ANSWER TYPE QUESTIONS
Q1. Algae are divided into three main classes. What
are three classes?
Differentiate them based uponphotosynthetic pigments
and reserve food.
A18
INTRODUCTION:BRYOPHYTES
The term Bryophyta originates from the word ‘Bryon’ meaning mosses and ‘phyton’
meaning plants. These are small plants that grow in shady and damp areas. They
lack vascular tissues (xylem and phloem). They don't produce flowers and seeds,
instead, reproduce through spores. They are also called “Amphibians of the
plant kingdom” because they are terrestrial plants but require water to
complete their life cycle at the time of sexual reproduction.
GENERAL CHARACTERISTICS OF BRYOPHYTES
Plants occur in damp and shady areas.The plant body is thallus like prostrate
or erect.
It is attached to the substratum by rhizoids which
are unicellular or
multicellular. They lack true vegetative structure
and have a root like, stem like and leaf like structure.Plants lack the
vascular system (xylem, phloem).There is heterologous or heteromorphic
alternation of generation.Gametophyte and sporophyte are morphologically very
different.The dominant part of plant body is gametophyte which is haploid.The
thalloid gametophyte is differentiated into rhizoids, axis and
leaves.Gametophyte bears multicellular and jacketed sex organs as well as is
photosynthetic.
The male _sex organ is called Antheridium. \t
produces biflagellate
antherozoids.The female sex organ is called
Archegonium. It is flask shaped and produce single egg. The Antherozoids fuse
with egg to form a zygote.Zygote develops into multicellular diploid
sporophyte.
The sporophyte is semi-parasitic and depends on the
gametophyte for
its nutrition.Cells of sporophyte undergo meiosis to
form haploid gametes which form a haploid gametophyte.The juvenile gametophyte
is known as protonema.The sporophyte is differentiated into foot, seta and
capsule.
CLASSIFICATION OF BRYOPHYTES
There are three classes in Bryophyta:-
1. Hepaticopsida (Liverworts)
2. Bryopsida (Mosses)
3. Anthocerotopsida (Hornworts)
1. Hepaticopsida (Liverworts)
The main body in the life cycle of gametophyte which is dorsiventral and
thalloid. Rarely some liverworts are leafy e.g. Porella. Thallus has
unicellular unbranched rhizoids which help in fixation and absorption. The
thallus is dichotomously branched.e Vascular system (xylem and phloem) is
absent.Photosynthetic tissue is absent in sporangium. So, it is total parasite
on
gametophyte. Stomata, peristome teeth and columella are
absent in sporangium. Protonema stage is absent in life cycle e.g. Riccia,
Marchantia, Porella. Sex organs are embedded in thallus.
REPRODUCTION:
a) ASEXUAL REPRODUCTION:
- It takes place by fragmentation or by
formation of gemmae. Gemmae are produced inside
gemma cups. The
gemma cups develop into new plant after detaching
from the parent
plant.
b) SEXUAL REPRODUCTION: -
Antheridium (male sex organ) and
Archegonium (female sex organ) may be present on
same thalli or
different thalli. Sex organs are multicellular and
jacketed. The male
sex organ Antheridium produces biflagellated
antherozoids. The female
sex organ Archegonium is flask shaped and produces a
single egg.
After fertilization zygote is formed. The zygote
develops into diploid
sporophyte undergo meiosis to form haploid spores.
These spores
develop into haploid gametophytes, which is free
living and photosynthetic.
2. Bryopsida (Mosses):It
is the largest class of Bryophyta with around 1400 species. They are commonly
called mosses e.g. Funaria, Polytrichum, Sphagnum.The predominant stage of life
cycle of mosses is gametophyte which consists of two stages. The first stage is
protonema stage which is formed by germination of meiospore. It is creeping,
green branched and filamentous stage.The second stage of gametophytic
generation is leafy stage which develops from secondary protonema as lateral
bud. They consist of upright slender axis bearing spirally arranged leaves.
They are attached to soil by multicellular and branched rhizoids.Vascular tissue
is absent.In mosses stem and leaves are not true because they lack vascular
tissues and are haploid.
REPRODUCTION:
a) ASEXUAL REPRODUCTION:
Asexual reproduction is by fragmentation
and budding of secondary protonema.
b) SEXUAL REPRODUCTION:
Sex organs Antheridia (male sex organ),
and Archegonia (female sex organ) are produced at
the apex of leafy
shoots. After fertilization zygote develops into a
sporophyte called
sporogonium. Sporogonium is divided into foot, seta,
columella and
capsule. Photosynthetic tissues are present in
capsule. It is a semi-
parasite on gametophyte. Capsule contains spores
which are formed
after meiosis. The gametophyte develops from the
spores. Peristome
teeth are present in capsule which helps in
dehiscence and dispersal of spores.
LET US KNOW WHAT WE HAVE LEARNT !
PART- A) VERY SHORT ANSWER TYPE
QUESTIONS: -
a) MULTIPLE CHOICE QUESTIONS
Q-1 Plant body is
dorsiventral and prostrate showing dichotomous branching:
a) Liverworts
b) Mosses
c) Funaria and Sphagnum
d) None of these
Q-2 Protonema and
leafy stage are the predominant stage of the life cycle of:-
a) Mosses
b) Dicots
c) Liver worts
d) none of these
Q-3 The unique
feature of Bryophytes compared to other plant groups is that:-
a) They produce spores
b) They lack vascular tissues
c) They lack roots
d) their sporophyte is attached to Gametophyte
Q-4 In
Bryophytes, male and female sex organs are called__and__respectively:
a) Microsporangia, Megasporangia
b) Male strobili, Female strobili
c) Antheridia, Archegonium
d) Androecium, Gynaecium
Q-5 Mosses don’t
have true leaves because their leaf like structure lack:-
a) Starch in their chloroplasts
b) Vascular tissues
c) Chlorophyll
d) Cellulose in their cell wall
b) TRUE /FALSE
Q-6 The sex organs in Bryophytes are unicellular and
naked.
Q-7 Vascular bundle is present in Bryophytes.
Q-8 Thallus is dichotomous and branched in
Bryophytes.
C) FILL IN THE BLANKS
Q-9 Asexual reproduction in Liverworts takes place
by_—s and _.
Q-10 Peristome teeth are present in .
PART- B) SHORT ANSWERS TYPE QUESTIONS:-
Q-1 Why Bryophytes are called “Amphibians of plant
kingdom"?
Q-2 Write about sexual reproduction in Liverworts?
Q-3 Define Gemma?
PART- C) LONG ANSWERS TYPE QUESTIONS: -
Q-1 Explain the general characters of Bryophytes?
ANSWER KEY: PART-A
a) MULTIPLE CHOICE QUESTIONS
ANS-1. a) Liverworts
ANS-2 a) Mosses
ANS-3 d)
Their sporophyte is attached to gametophyte.
ANS-4_ c) Antheridia, Archegonium.
ANS-5 _ b) Vascular tissues.
b) TRUE / FALSE
ANS-6 FALSE (Multicellular and Jacketed)
ANS-7 FALSE (Vascular bundle is absent in
Bryophytes)
ANS-8 TRUE
c) FILL IN THE BLANKS
ANS-9 Fragmentation and Gemmae.
ANS-10 Capsule
A19
INTRODUCTION:Students we have discussed in previous assignment about bryophytes, their different types and characteristics. Now we will discuss here about the ecological and economic importance of Bryophytes.
ECOLOGICAL AND ECONOMIC IMPORTANCE OF
BRYOPHYTES:
Bryophytes have great ecological importance. Mosses and lichens are the first organisms to colonise rocks.
MEDICINAL USES:Sphagnum is used
in surgical dressing due to its high absorptive power and some antiseptic
properties.Marchantia has been used to cure pulmonary tuberculosis and
infections of liver.Dried sphagnum is used in the treatment of eye
infections.Polytrichum is used to dissolve kidney and gall bladder
stones.Antibiotic substances can be extracted from certain bryophytes having
antibiotic properties.
IN RESEARCH:
Mosses and liverworts are used in research in the field of genetics.
IN PACKING MATERIAL:Dried mosses
make an excellent packing material for fragile goods like glassware, bulbs etc.
FOOD:Some mosses
provide food for herbaceous mammals, birds and other
mammals.
AS INDICATOR PLANTS:
Polytrichum indicates the acidity of soil.
IN SEEDBEDS:
Because of its water retention capacity, it is used in seedbeds, green-houses,
nurseries to root cuttings. Sphagnum is used to maintain high soil acidity
required by certain plants.
PEAT FORMATION:Some species of
sphagnum provide peat which is used as fuel.Peat is also used in the production
of ethyl alcohol, ammonium
sulphate, ammonia, dye, paraffin etc.It improves
soil texture in horticulture.
a) MULTIPLE CHOICE QUESTIONS:
Q-1 Mosses are of
great ecological importance because of: -
a) Its contribution to prevent soil erosion.
b) Its contribution in recycling nutrients in the
soil.
c) Its capability to remove CO from atmosphere.
d) Both (a) and (b).
Q-2. Which are
the first organisms to colonise rocks?
a) Sphagnum and Polytrichum.
b) Algae and Fungi.
c) Mosses and Lichens.
d) All of these.
Q-3 Which plants
are used for the research in the field of genetics?
a) Mosses and Liverworts.
b) Polytrichum and Porella.
c) Both (a) and (b).
d) None of these.
Q-4 Peat is used
for the production of:
a) Ethyl alcohol.
b) Ammonium sulphate.
c) Dye and paraffin.
d) All of the above.
Q-5 Which of the
following is used as fuel?
a) Fungi.
b) Laminaria.
c) Sphagnum.
d) Both (a) and (b).
b) TRUE / FALSE -
Q-6 Some Bryophytes are used as an indicator for the
detection of acidity of soil.
Q-7 Bryophytes improve the texture of the soil.
Q-8 Bryophytes don't prevent the soil erosion.
c) FILL INTHE BLANKS:
Q-9 Polytrichum species are used for the treatment
of sand ___.
Q-10__ is used to maintain soil acidity required by
certain plants.
Q-1 Write the importance of Sphagnum?
Q-2 Why dried mosses are in for packaging materials?
Q-3 Write the importance of polytrichum?
Q-1 Write any five ecological importances of
bryophytes?
a) MULTIPLE CHOICE QUESTIONS:
ANS-1 (d) Both (a) and (b).
ANS-2 (d) All of these.
ANS-3 (a) Mosses and Liverworts.
ANS-4 (d) All of the above.
ANS-5 (c) Sphagnum.
b) TRUE / FALSE:
ANS-6 TRUE.
ANS-7 TRUE.
ANS-8 FALSE. (Bryophytes improve the texture of
soil)
c) FILL IN THE BLANKS
ANS-9 Kidney, gall bladder stones.
ANS-10 Polytrichum.
A20
INTRODUCTION:Dear
students, we have covered Algae and Bryophytes among plants in chapter , plant
kingdom.Today we will study about next group of plants:
PTERIDOPHYTES.Pteridophytes are the first terrestrial plants. They are seedless
and have vascular tissues.
CHARACTERISTICS OF PTERIDOPHYTES:The
pteridophytes include HORSETAILS and FERNS.The pteridophytes are found in cool,
damp, shady and_ in sandy soils conditions.Evolutionary, they are the first
terrestrial plants and possess vascular tissues- xylem and phloem.Xylem
transports water and minerals while phloem conducts organic food.The main plant
body is a sporophyte which is differentiated into true root,stem, and
leaves.The leaves in pteridophyta are small (microphylls) as in Selaginella or
large (macrophylls) as in ferns.The sporophytes bear sporangia, that are
subtended by leaf-like appendages called sporophylls.In some cases sporophylis
may form distinct compact structures called strobili or cones (Selaginella,
Equisetum).
The sporangia produce spores by meiosis in spore
mother cells.
In majority of pteridophytes all the spores are of
similar kinds and are known as homosporous (Lycopodium, Dryopteris).Genera like
Selaginella and Salvinia which produces two kinds of spores,
macro (large) and micro (small) spores, are known as
heterosporous.
The megaspore germinates to give female gametophyte
and microspore
germinates to give male gametophytes.The
gametophytes bear male sex organs called antheridia and female sex organs,
archegonia.
The gametophyte that develops in homosporous species
is monoecious
(having male and female reproductive structures on
the same individual) while those of heterosporous species is dioecious (having
the male and female reproductive structure on different individuals).
Male gametes (antherozoides) are flagellated. They
require an external
supply of water for swimming to the mouth of
archegonium (female
gamete).Fusion of gametes results in the formation
of zygote which develops into young embryo. The embryo develops into a
multicellular well-differentiated sporophyte.In the heterosporous species, the female
gametophyte remains on the parent sporophytes for variable periods. The
development of the zygotes into young embryos takes place within the female
gametophytes. This event is a precursor to the seed habit (tendency towards
seed formation) considered an important step in evolution. Hence, heterospory
leads to seed habit in plants.
THE PTERIDOPHYTES ARE CLASSIFIED INTO
FOUR CLASSES:
(1) PSILOPSIDA: ( WHISK FERNS)
Simplest and oldest vascular plants.Rhizoids in
place of roots.
Leaves absent or few.
(2) LYCOPSIDA: (CLUB MOSSES)
Plants with TRUE roots, stem and leaves.
Sporophylls aggregated to form strobili or cones.
Stem and roots show branching
(3) SPHENOPSIDA:
(HORSE TAILS or SCOURING RUSH)
Stem is jointed.Leaves and branches in whorls on the
nodes.
EQUISETUM is the only living species, called LIVING
FOSSIL.
(4) PTEROPSIDA OR PHILICOPSIDA OR FERNS:Seedless
vascular plants.
Megaphyllous leaves show circinate ptyxis
(coiled).Megaphylous leaves bear sporangia in sori.
ECONOMIC IMPORTANCE OF PTERIDOPHYTES:
(i) Soil binding: Pteridophytes bind the soil even
along hill slopes. The soil is protected from erosion.
(ii) Medicines: An anthelmintic drug is obtained
from a pteridophyte called Dryopteris.
(iii) Ornamentals: Ferns are grown as ornamental
plants for their delicate and graceful leaves.
(iv) Food: Marsilea, a water fern yields starch that
constitute a good source of food for certain tribals.
(v) Scouring: Equisetum stems have been used in
scouring (cleaning utensils) and polishing of metals.
LET US KNOW WHAT WE HAVE LEARNT!
PART-A VERY SHORT ANSWER TYPE
QUESTIONS:
(a) MCQs:
1. A plant that
possesses vascular tissues is:
(a)Funaria
(b) Equisetum
(c) Polytrichum
(d) Sphagnum
2. The plant body
is differentiated into true root, stem and leaves in:
(a) Selaginella
(b) Marchantia
(c) Porphyra
(d) Chara
3. Antherozoids
represents:
(a)Male gametophyte
(b)Photosynthetic prothallus
(c)Motile male gametes
(d)Well differentiated sporophyte
4. After
germination the megaspore give rise to:
(a) Female gametophyte
(b) Antheridia
(c) Male gametophyte
(d) Antherozoid
5. In
pteridophytes, fusion of gametes takes place in:
(a) External medium
(b) Antheridium
(c) Sporangium
(d) Archegonium
b) TRUE / FALSE:
1. Ferns are mostly found in dry climate.
2. In selaginella gametophytes is dominant
generation.
3. The fern is hetesporous.
c) FILL UPS:
1. In pteridophytes branching is never .
2. Ferns contain underground stem called .
3. The pteridophytes include and .
A. MCQs:
1. (b) Equisetum. (Hint: Others are bryophytes)
2. (a) Selaginella (Hint: Marchantia-bryophytes,
porphyria and chara-algae)
3. (c) Male gametes (Hint: Male gametes produced in
antheridia)
4. (a) Female gametophyte
5. (d) Archegonium
B. TRUE/ FALSE:
1. False ; ( Hint: Ferns are found in moist and
shady places.)
2. False: (Hint: sporophyte is dominant generation)
3. False; (Hint: Most of the ferns are homosporous.
)
C. FILL UPS:
1. Axillary
2. Rhizome
3. Horsetails and Ferns
PART-B SHORT ANSWER TYPE QUESTIONS:
1. What are sporophylls?
2. Why Selaginella is known as heterosporous?
3. What is monoecious and dioecious condition?
PART-C LONG ANSWER TYPE QUESTIONS:
1. Describe the main features of Pteridophytes.
2. Write a note on economic importance of
Pteridophytes.
A21
INTRODUCTION:So
far we have studied about ALGAE, BRYOPHYTES and PTERIDOPHYTES under Plant
Kingdom, in chapter- 03.Now let us discuss about GYMNOSPERMS.
GYMNOSPERMS:
(gymnos: naked, sperma : seeds )The gymnosperms are NON-FLOWERING, SEED plants
in which the ovules are not enclosed by any ovary wall and remain exposed both
before and after fertilisation.
They are the naked seed plants without fruits.
THE MAIN CHARACTERISTICS OF GYMNOSPERMS
ARE:
1. They include medium - sized trees or tall trees
and shrubs. The sequoia (red wood tree) is one of the tallest tree species.
2. Plant body is differentiated into roots, stem,
and leaves.
3. The roots are generally tap roots. Roots in some
genera have fungal
association in the form of mycorrhiza (Pinus), while
in some others (Cycas) small specialised roots called coralloid roots are
associated with nitrogen fixing Cyanobacteria.
4. The stems are unbranched (Cycas) or branched
(Pinus, Cedrus)
5. The leaves may be simple or compound. In Cycas
the pinnate leaves persist for a few years.In simple leaf, there is a single
lamina which is usually entire.In compound leaf incision of lamina reaches up
to the midrib or petiole due to which lamina is divided into several small
parts known as leaflets.
6. The leaves in gymnosperms are well- adopted to
withstand extremes of temperature, humidity, and wind. In conifers, the needle-
like leaves reduce the surface area. Their thick cuticle and sunken stomata
also help to reduce water loss. Leaves of Ginkgo biloba are fan- shaped.
7. They have well- developed vascular tissue— xylem
and phloem.
8. Gymnosperms are heterosporous_and produce haploid
smaller micro
spores and larger megastores. The two kinds of
spores are produced within Sporangia that are borne on sporophylls which are
arranged spirally along an axis to form lax or compact strobilli or cones.
9. Sporophylls are of two types: Microsporophylls
and megaporophylls.
10. The Strobilli bearing microsporophylls and
microsporangia are called microsporangiate or male strobilli. They bear
microsporangia where microspore mother cells undergo meiosis to form
microspores. The microspores develop into a male gametophytic generation which
is highly reduced and is confirmed to only a limited number of cells. This
reduced gametophyte is called a pollen grain. The development of pollen grains
takes place within the microsporangia.
11. The cones bearing megasporophylls with ovules or
megasporangia are
called macrosporangiate or female strobili.
12. The males or female cones or strobili may be
borne on same tree (Pinus) or on different trees (Cycas).
13. The megaspore mother cell is differentiated from
one of the cells of the nucellus. The
nucellus is protected by envelopes and the composite structure is called an
ovule.
14. The ovules are borne on megasporophylls which
may be clustered
to form the female cones.
15. The megaspore mother cell divides meiotically to
form four
megaspores of which three degenerates.
16. One of the megaspores enclosed within the
megasporangium (nucellus) develops into a multicellular female gametophyte that
bears two or more archegonia or female sex organs. The multicellular female
gametophyte is also retained within megasporangium.
17. During pollination, the pollen grains are
carried in air currents and reach the opening of the ovules borne on
megasporophylls.
18. Each pollen grain germinates, and the resulting
pollen tube discharges the male gametes near the mouth of the archegonia.
19. Fertilisation results in the formation of
zygote, which develops into an embryo and the ovules into seeds.
20. These seeds are not covered.
ECONOMIC IMPORTANCE OF GYMNOSPERMS:
(1) EDIBLE SEEDS:
Seeds of Pinus gerardiana called chilgoza are edible.
(2) TIMBER:
Gymnosperms possess softwood.It is used in preparation of light furniture,
plywood, packing cases, match-sticks, railway sleepers, etc.
(3) PAPER: A number of
gymnosperms are used in the manufacture of paper.
(4) FIBRE BOARDS:
Needle of Pinus and other conifers are used in making fibre boards that are
used in packing cases.
(5) EPHEDRINE:
Drug ephedrine is obtained from Ephedra, a gymnosperm.
(6) TAXOL:
An anti-cancerous drug, called Taxol, is obtained from the bark of Taxus.
PART: A VERY SHORT ANSWER TYPE
QUESTIONS:
(a) MCQs:—
1. One of the tallest
tree species is:
(a) Pinus
(b) Sequoia
(c) Cycas
(d) Cedrus
2. Coralloid root
is the feature of:
(a) Cycas
(b) Mosses
(c) Pinus
(d) Selaginella
3. The
gymnosperms pollination generally occurs by:
(a) Air currents
(b) Water
(c) Insects
(d) Both (b) and (c)
4. In
gymnosperms, the pollen tubes discharge the male gametes:
(a) In the ovary
(b) In the microsporangia
(c) Near the mouth of the archegonia
(d) both b and c
5. The largest
antherozoids are found in:
(a) Cycas
(b) Cedrus
(c) Ephedra
(d) Pinus
(b) TRUE /FALSE:-—
1. Ginkgo biloba is called living fossil.
2. Gymnosperms are naked seeded plants.
3. Megaspore on germination produces female
gametophyte.
(c) FILL UPs:-
(1) Cones represents the.............. organs in the
gymnosperms.
(2) .......... roots are found in some gymnosperms
like Cycas.
(3) The largest antherozoids are found
in............
ANSWER KEY: PART-A
a) MCQs-
1. (b) The Sequoia (Hint: red wood tree)
2. (a) Cycas (Hint: specialised roots associated
with nitrogen- fixing
Cyanobacteria)
3. (a) Air currents
4. (c) Near the mouth of archegonia
5. (a) Cycas
b} True or False :-
1. True
2. True
3. True
A22
INTRODUCTION:ANGIOSPERMS
(FLOWERING PLANTS)
These are seeded plants which are kept under
SPERMATOPHYTA. Seeds are enclosed in fruits. These plants are most evolved
plants of the plant kingdom. These plants are appeared on earth about 145
million years ago. In angiosperms sporophylls are organized into flowers. The
smallest plant in angiosperm is WOLFIA less than 1mm.
CHARACTERISTICS OF ANGIOSPERMS
:Angiosperms are mostly terrestrial.
The main plant body in the life cycle is a
sporophyte which is divided into roots,stem and leaves.Reticulate venation in
dicot and parallel venation in monocot leaves.Stamens and carpels are essential
parts of flower.Androecium is the male part of flower while gynoecium is the
female part of flower.A carpel has many ovules borne on placentae inside
ovary.Fertilization siphonogamous type.There is double fertilization in
angiosperms.Ovary is ripened to form fruit which encloses seeds.Embryo
development is meroblastic type.Endosperm is 3N but in gymnosperms it is
haploidiN.Time interval between pollination and fertilization is very
small.Presence of secondary growth in dicots.An ovule enclosed female gametophytes
which is eight nucleated.
Male gametophyte is enclosed in pollengrains.
GROWTH PATTERNS IN ANGIOSPERMS:LONGEVITY
The length of period for which a plant survives is called longevity. It is
further of many types:
Ephemerals — these are plants which live for several
weeks only.
Eg- artemesia and astragalus.
Annuals — these are plants which live for one
favourable season
only. Eg- wheat and rice
Biennials — These plants complete their life in two
years. Eg-
radish and turnip.
Perennials- These plants live for many years. Eg-
apple and
guava.
SIZE:Wolffia is the smallest angiosperms. it is
about 1mm in diameter
and is free floating hydrophyte and Eucalyptus
regnans is the
longest; 114 meter and above.
HABIT:Depending upon the habit,angiosperms are of
many types:
1. Herbs: They are small plants with soft and
pliable stems which
normally grow to a height of less than 2m. Herbs may
be annual (e.g.,
Wheat, Buttercup), biennial (e.g. Henbane) or
perennial (e.g., Canna).
The perennial herbs have either water conserving
mechanism or possess
underground stem which produces new shoots every
year.
2. Shrubs: Plants are of medium height with
perennial woody
stems. A trunk is absent. Many stem branches of
equal height may
arise from near the base. They are woody below and
herbaceous near the
apices. Shrubs are also called bushes, e.g.,
Capparis, Jasmine, and
Rose.
3. Trees:Plants are of great height with a thick
woody main stem called trunk. The trunk may remain un-branched when it is
called caudex or columnar, e.g.,Palm. In ex-current form the trunk produces
narrow lateral brancheswhich do not compete with the former. The appearance is
cone-like, e.g.,Pinus, Casuarina, and Eucalyptus. In deliquescent type the
trunk disappears after some distance so that the crown appears dome
shaped,e.g., Dalbergia, Banyan.
4. Trailers spread over the ground without rooting
of prostrate stems,
e.g., Tribulus, Euphorbia.
5. Creepers have prostrate stems which root at
intervals, e.g., grass.
6. Twiners are weak stemmed plants where stems twine
around the
support, e.g., lpomoea.
7. Climbers rise up their support by means of
special clinging or coiling structures e.g., Grape Vine.
HABITAT:Angiospems
have various types of habitats:
HYDROPHYTE:Hydrophytes are
those plants which live in water and adjust with their surroundings. They
either remain fully submerged in the water like Hydrilla, Valisineria, etc. or
most of their body parts remain under the water like trapa, lotus, etc. water
lilies, sedges, crow foots are other important water plants.
MESOPHYTE:Mesophytes
are common land plants, which grow in situations that are neither too wet nor
too dry. These plants can neither grow in water or waterlogged soils nor can
they survive in dry places. In other words,mesophytes are the plants of those
regions where climates and soils are favourable.
XEROPHYTES:A
xerophyte (xero meaning dry, phyte meaning plant) is a plant which is able to
survive in an environment with little availability of water or moisture. Plants
like the cacti and other succulents are typically found in deserts where low
rainfall is the normal phenomen, but few xerophytes can also be found in moist
habitats such as tropical forests, exploiting niches where water supplies are
limited or too intermittent for mesophytic plants.
HALOPHYTES:These plants are found
in salina places. E.g salsola.
MODE OF NUTRITION:
1. Autotrophic mode of nutrition:It is also known as
holophytic mode (plant like nutrition).Organisms can synthesize all the
essential nutrients required for them from inorganic substrates (CO2, NH3,
nitrates, water etc) present in the environments. It is of two types.
Phototropic nutrition: Organisms synthesize their
food in the
presence of sun light using Carbon-dioxide and water
as substrate.
Such organisms are known as Photo-Autotrophs. Eg.
Green plants
2. Heterotropic mode of nutrition:Such Plants cannot
synthesize their food by themselves rather they depend on the food prepared by
Autotrophs (directly or indirectly).
Some of the examples of Parasite angiosperms are:Cuscuta, Rafflesia, Orabanche, Loranthus, Viscum, Santalum album Example of Saprophyte is Monotropa.
ANGIOSPERMS AS DICOTS & MONOCOTS Depending upon the
presence of one or two cotyledons in seed ANGIOSPERMS are of two types;
MONOCOTS and DICOTS.Angiosperms can be identified externally by having the
following information about them.
LET US KNOW WHAT WE HAVE LEARNT !
PART-A SHORT ANSWER TYPE QUESTIONS
a) MCQs:
Q1. A
characteristic of angiosperm is:
a) Root
b) Seed
c) Flower
d) All of the above
Q2. Which one of
the following is the saprophyte
a) Viscum
b) Balanophora
c) Monotropa
d) Loranthus
Q3. The ripened
and fertilized ovule is called
a) friut
b) Seed
c) endosperm
d) perisperm
Q4. The size of
smallest angiosperm wolffia is
a) Jum
b) imm
c) 2cm
d) 2mm
Q5. Which of the
following is an annuals plant?:
a) wheat
b) mango
c) guava
d) banyan tree
b) TRUE / FALSE:
Q1. There is double fertilization in angiosperms.
Q2. Hydrophytes are plants which are found in water.
Q3. Apple considered to be the tallest angiosperm
c) FILLIN THE BLANKS:
Q1. is the total stem parasite.
Q2. are mostly terrestrial.
Q3 is an insectivorous plant.
ANSWER KEY: PART-A
a) MCQs:
1. All of the above
2. Monotropa
3. Seed
4. 1mm
5. Wheat
b) TRUE/ FALSE:
1. TRUE (Hint: one is true fertilization ;egg &
male gamete,other is
vegetative; diploid secondary nucleus & one male
gamete (Tripple
fusion)
2. TRUE (Hint: Hydro means Water)
3. FALSE (Hint: Tallest angiosperm is Eucalyptus
regnans)
c) FILL IN THE BLANKS:
1. Cuscutta
2. Angiosperms.
3. Nepanthesis (Pitcher plant), Utricularia,
Drosera(Sundew) , Dionaea(Venus Flytrap).
PART-B SHORT ANSWER TYPE QUESTIONS
Q1. Differentiate between monocot and dicots.
Q2. Define creepers and twiners.
Q3. What do you mean by insectivorous plants.
PART-C LONG ANSWER TYPE QUESTIONS
Q1. Write the characteristic features of an
angiosperms.
A23
INTRODUCTION:There
are two different plant bodies Haploid and Diploid. Haploid plant body produce
gametes by MITOSIS. It is called Gametophyte. These HAPLOID gametes fuse or
fertilize and produce Diploid plant body ,called SPOROPHYTE. The sporophyte
produce haploid spores by meiosis. These Haploid spores divide by mitosis to
form haploid gametophyte again.
PLANT LIFE CYCLES AND ALTERNATION OF
GENERATIONS:The fusion product of gametes is a
diploid cell known as zygote.The distinct morphological and cytological stages
through which the growth and development of an organism passes, constitutes a
sequence of events known as life history or life cycle.
The life cycle consists of two distinct a phases:
haploid (gametophytic) and diploid (sporophytic) regularly alternating each
other, the phenomena is termed as alternative of generations.
HAPLONTIC LIFE CYCLE:For organisms with a haplontic life cycle, such as fungi and some of the green algae, the multicellular stage is haploid. In this case, as soon as the diploid zygote is formed, it undergoes meiosis to produce haploid spores inside structures called sporangia (sporangium,singular). Spores can be distinguished from gametes, not by how they are produced, but based on what they do afterward: spores grow, gametes fuse.
These haploid spores then grow by mitosis
to produce multicellular haploid organisms. These haploid organisms produce
haploid gametes by mitosis. In this life cycle, all of the gametes produced by
an organism are identical to each other and to the parent organism. These
haploid gametes can then fuse to form a diploid zygote. This is also called
zygotic meiosis because the zygote undergoes meiosis. In the life cycle
diagram, the zygote alone is the diploid portion.
DIPLONTIC LIFE CYCLE:Diplontic
life cycle refers to the life cycle of organisms, which is dominated by the
diploid stage. All the plants showing sexual reproduction alternate between two
multicellular stages, viz. Haploid gametophyte and diploid sporophyte.In the
diplontic life cycle, the diploid stage or sporophyte is the
dominant and Independent stage of the plant and_
performs
photosynthesis. The haploid phase is represented by
single-cell gametes or few celled gametophytes.Here mitosis usually occurs at
the diploid zygote stage, and gametes are produced by meiosis.
DIPLONTIC LIFE CYCLE
HAPLO- DIPLONTIC LIFE CYCLE:This type of life cycle is found typically in ALGAE like Ectocarpus,BRYOPHYTES and PTERIDOPHYTES etc.It consist of two distinct vegetative phases alternating with each other which are different cytologicaliy and functionally.The haploid gametophyte produces gametes in sex organs. The gametes fuse to form diploid zygote, which on germination gives rise to diploid sporophyte, thus meiosis occurs at the time of spore formation.In BRYOPHYTES and PTERIDOPHYTES both phases are multicellular,however they are different dominant phases.
In BRYOPHYTES a green
independent thalloid phase is
present in the form of haploid gametophyte.It bears
a short lived multicellular sporophyte which is partially or totally dependent
on gametophyte for the purpose of nutrition.However in PTERIDOPHYTES
sporophytes is represented by a dominant independent photosynthetic vascular
plant body.It bears a small lived haploid gametophyte, which is independent
multicellular autotrophic or saprophytic.
LET US KNOW WHAT WE HAVE LEARNT!
PART-A (VERY SHORT ANSWER TYPE
QUESTIONS)
a} MCQs
1. Which two
groups of plants produce seeds?
(a)Gymnosperms and angiosperms
(b)Bryophytes and ferns
(c)Angiosperms and bryophytes
(d)Angiosperms and ferns
2. Which one of
the following has haplontic life cycle?
(a) Pdytrichum
(b) Ustilago
(c) Wheat
(d) Funaria
3. Life cycle of
Ectocorpos and Fucus respectively are:
(a)Diplontic and haplo diplontic
(b)Haplo diplontic and diplontic
(c)Haplo diplontic and haplontic
(d)Haplontic and diplontic
4. Which of the
following are the examples of haplontic life cycle?
(a) Chara
(b) Spirogyra
(c) Oedogonium
(d) all of the above
5. Which are
morphological life cycles recognized in algae?
(a) Haplontic
(b) Diplontic
(c) Diplohaplontic
(d) all of the above
b) FILL IN THE BLANKS
1. Haplontic life cycle is found in
2. Type of life cycle found in Ectocarpus algae,
c) TRUE /FALSE
1. The algae Fucus shows diplontic life cycle.
2. Prothallus in Marchantia shows haploid life
cycle.
3. Haplontic life cycle is found in gymnosperms and
Angiosperms
ANSWER KEY: PART-A
a) MCQS
1. (A)
2. (B)
3. (B)
4. (D)
5. (D)
b) Fillin the blanks
1. Algae
2. Haplodiplontic
c) True/False
1. True
2. True
3. False (Hint: Diplontic life cycle is found in
seed
plants.)
PART B (SHORT TYPE QUESTION ANSWER)
1. With the help of schematic diagram, describe the
haplo-diplontic
life cycle pattern of a plant group.
2. What do you understand by haplontic life cycle?
3. What is diplontic life cycle? Give examples.
PART C (LONG TYPE QUESTION ANSWER)
1. Explain haplo-diplontic life cycle in bryophytes.
2. Differentiate between haplontic and diplontic
life cycle.
A24
INTRODUCTION:Hello
students, as you have completed the chapter, Plant Kingdom.In this we studied
different divisions of plant kingdom.
Now we will discuss all the difference or comparison
type
questions, in this assignment of Daily Dose.
The various Scientists classified plants according
to so many types of
classification systems. Some of these are:
1. Artificial classification System
2. Natural classification System
3. Phylogenetic classification System
4. Phenetic classification System
Difference between Natural and Artificial
Systems:Natural system Artificial system
1 Characters are stable. 1 Liable to change with
change in
environment
2 Does not use analogy 2 Use analogy for the purpose
of
grouping
3 Brings out homology 3 it does not study homology
Difference between natural and phylogenetic systems:
NATURAL SYSTEM PHYLOGENETIC SYSTEM
1. Based on number of constant 1. Based on
evolutionary sequence
characters
2. More practical utility 2. Lesser practically
utility
3. Role of fossil give little significance 3. Fossil
provides vital information
PHENETIC CLASSIFICATION system includes, Numerical
Taxanomy, Cyto
Taxonomy, Chemotaxonomy and Cladistic Taxanomy.
CYTOTAXONOMY CHEMOTAXONOMY
1. Based on cellular characters. {. tt based on
chemical constitution.
2. It based on number of 2. It based on the chemical
constituent of
chromosomes and their behavior. | chromosomes.Numerical Taxanomy uses statistical methods.Cladistic taxanomy is based on shared derived characters that are different from ancestral characters.
THALLOPHYTA is the most primitive and simple of all plants. It
includes Algae and Fungi.On the basis of CHLOROPHYLL PIGMENTS Algae are of
three types:
RED ALGAE (Rhodophyceae)
BROWN ALGAE (Phaeophyceae)
GREEN ALGAE (Chorophycea)
COMPARISON AMONG RED, BROWN AND GREEN
ALGAE:CLASSES COMMON MAJOR STORED FLAGELLAR NAME PIGMENTS
FOOD
The plants body of bryophytes is more differentiated than that of algae.Differences between Liverworts and mosses
Liverworts Mosses Its symmetry is dorsiventral
Radial symmetry is present Capsule is simple Complex capsule divide into
Plants body is thalloid or apophysis ,theca and
operculum
foliose Plants body is foliMose Midrib is absent in
leaves Non vascular midrib Protonema is absent Protonema is present
LIFE CYCLES:
The plants represent morphologically distinct generations, i.e, GAMETOPHYTIC
and SPOROPHYTIC.
DIFFERENCES BETWEEN SPOROPHYTE AND GAMETOPHYTE
SPOROPHYTE GAMETOPHYTE
1. Multi cellular diploid structurein 1.
Multicellular haploid structure the life cycle of a plant. present in life
cycle
2. Produces spores after meosis. 2. Produces gametes after meosis.
3. Take part in asexual reproduction 3. Take part in sexual reproduction
The sporophytes are partially or completely dependent upon
gametophyte. At maturity, the gametophyte produces gametes. The Male sex organ
is called ANTHERIDIUM and Female sex organ is called ARCHEGONIUM.
COMPARISON BETWEEN ANTHERIDIUM AND ARCHEGONIUM
PTERIDOPHYTES:PTERIDOPHYTES
includes Horsetail and Ferns.The main plant body is differentiated into true
stem, roots and leaves.
There is a typical heteromorphic alternation of
sporophytic and gametophytic generations.Sporophytic or asexual generation is
diploid.
It produces two types of spores; homosporous and
heterosporous.
LET US KNOW WHAT WE HAVE LEARNT!
PART A: VERY SHORT ANSWER TYPE
QUESTIONS
M.C.Qs:
1. In Bryophytes
and Pteridophytes, medium of transport for gametes:
a) Wind
b) Bird
c) Insects
d)Water
2. Protonema is :
a) Haploid and is found in mosses
b) Diploid and is found in liverworts
c) Diploid and is found in pteridophytes
d) Haploid and is found in pteridophytes
3. Plants need
water to complete its life cycle because the male gametes are motile. Identify
the group:
a) Bryophytes
b) Dicots
c) Pteridophytes
d) Algae
4. Marchantia,
Ricca, Anthoceros are:
a) Mosses
b) Liverworts
c) Red algae
d) Brown algae
5. Chorophycea is
type of:
a) Red algae
b) Brown algae
c) Green algae
d) White algae
FILL IN THE BLANKS:
1. Sporophytes produces .........spores.
2. ........Chlorophyll pigments present in red
algae.
3. Selaginella and Equisetum are...........
TRUE / FALSE:
1. Male thallus of Marchantia bear antheridiophore.
2. Megaspore on germination produces female
gametophyte.
ANSWERS KEY: PART-A
a) MCQs:
1. d (because, male gametes are motile)
2. a (It develop from haploid spores)
3. a (Bryophytes has multicellular thalloid)
4. b (Have thallus like body)
5. c (Due to presence of chlorophyll pigments a
& d.
b) Fill ups:
1. Haploid
2. Chlorophyl a and d
3. Pteridophytes
c) True/false:
1. True
2. True
PART B. SHORT ANSWER TYPE QUESTIONS:
Q1. What are the major differences between Natural
and Artificial system of classification?
Q2. Compare among Red, Brown and Green algae.
Q3. Compare between Cytotaxonomy and Chemotaxonomy.
PART C.LONG ANSWERS TYPE QUESTIONS
Q1.How Bryophytes are different from Pteridophytes?
Q2. Differentiate between Thallophytes (Algae) and
Bryophytes.
A25
INTRODUCTION:As
we have already studied in Daily Dose- 24 that Seed bearing plants are called
as SPERMATOPYTES. Spermatophytes are further divided into two sub- groups:
1) GYMNOSPERMAE (with naked seeds)
2) ANGIOSPERMAE (with covered seeds)
COMPARISON BETWEEN GYMNOSPERMS AND ANGIOSPERMS
Unlike Bryophytes and Pteridophytes, in Gymnospermsthe male and
female gametophytes do not have an independent
free-living existence.
They show syngamy.But Angiosperms due to involvement of two fusions of nuclei, show the event of Double Fertilization. One male gamete fuses with egg cell (Syngamy) and other fuses with diploid secondary nucleus.(Triple fusion)
SYNGAMY TRIPLE FUSION It is the fusion of male and It
is fusion of second male .female gametes gamete with diploid nucleus Forms
zygote Forms triploid endosperm Zygote forms embryo Endosperm provides
nourishment to embryo Occurs in animals and plants Occurs in angiosperms
The angiosperms are divided into two classes:
1. Monocotyledons
2. Dicotyledons
Monocots plants are Bamboo, Grasses, Sugarcane,
Bananas,Lilies, cereals (Like Wheat, Rice, Maize). Dicots include plants of all
During the life cycle of any sexually reproducing plants, there is
Alternation Of Generations .It shows different
pattern of life cycles i.e
1 HAPLONTIC LIFE CYCLE
2 DIPLONTIC LIFE CYCLE
Differences between HAPLONTIC and
DIPLONTIC life cycles:
LET US KNOW WHAT WE HAVE LEARNT!
PART: A VERY SHORT ANSWER TYPE
QUESTION:
MCQs
1. The embryo sac
of angiosperms is made up of
a. 8 cells
b. 7 cells and 8nuclei
c. 8 nuclei
d. 7cells and 7 nuclei
2. The plant
which is called living fossil:
a. Cycas
b. Pinus
c. Ginkgo
d. Wolffia
3. Double
fertilization occurs in:
a. Pteridophyte
b. Bryophytes
c. Angiosperms
d. Gymnosperms
4. Primary
endosperm nucleus in angiosperms give rise to:
a. Double endosperm
b. Single endosperm
c. Triploid endosperm
d. No endosperm
5. Endosperm
provides:
a. Protection to developing embryo
b. Nourishment to developing embryo
c. Nourishment to fruit
d. Protection to ripe fruit
TRUE/FALSE
1. Double fertilization occurs in gymnosperms.
2. Sugarcane and cereals are examples of
monocotyledons .
3. Spermatophyta means seedless plants.
FILL IN THE BLANKS
1. The gymnosperms are .......seeded plants where as
angiosperms
are ...........plants.
2. ...++.18 the female gametophyte in angiosperms.
ANSWER KEY: PART-A
MCQs:
1. b
2. c (Ginkgo the maiden hair tree only single
species )
3. ¢
4. c (fusion of second male gamete with diploid
secondary nucleus)
5. b
TRUE/FALSE:
1. False (It occurs in angiosperms)
2. True
3. False (It means seed bearing plants or
Phanerogams)
FILL IN THE BLANKS:
1. Naked, fruits bearing plants
2. Embryo sac
PART B: SHORT TYPE QUESTIONS:
Q1. Comparison between monocotyledons and
dicotyledons
O2. What is the differences between syngamy and
triple fusion
Q3. How haplontic life cycle is different from
diplontic life cycle.
PART C: LONG ANSWER TYPE QUESTIONS:
Q1. Differentiate between Angiosperms and
Gymnosperms.
A26
INTRODUCTION:Hello
Students, we have completed the chapter no.03 - PLANT KINGDOM,now we will
revise and recapitulate the lesson and then we will do the NCERT exercise
questions.
PLANT KINGDOM:It
includes all the plants that are
Eukaryotic,Multicellular and Autotrophic in nature. Plant kingdom is
divided into Algae, Bryophytes, Pteridophytes,Gymnosperms and Angiosperms.
CLASSIFICATION:Artificial
system: It was given by Carlous Linnaeus. Gross superficial morphological
characters were used in it and were based mainly on vegetative characters or
the androecium structure.
Natural classification: based on natural affinities
among the
organisms and consider not only the external
features, but also internal features.
Phylogenetic classification: based on evolutionary
relationships
between various organisms which assume that
organisms belonging to
the same taxa have a common ancestor.
TAXONOMY:Numerical
Taxonomy : based on all observable characteristics, where number and codes are
assigned to all the characters and the data are then processed.
Cytotaxonomy :
based on cytological information like chromosome
number, structure, behavior.Chemotaxonomy : based on
the chemical constituents of the plant.
DIVISIONS OF PLANT KINGDOM:
ALGAE:These include
the simplest plants which possess undifferentiated or thallus like forms,
reproductive organs single celled called
gametogonia. It includes only Algae.
CHARACTERISTICS OF ALGAE:Plant
body is thallus, which may be unicellular, colonial, filamentous or
parenchymatous.
Usually aquatic but a few are also found in moist
terrestrial habitats like tree trunks, wet rocks, moist soil, etc.
Vascular tissues and mechanical tissues are absent.(Chlamydomonous) or Oogamous ( Volvox).Life cycle can be- haplontic, diplontic or diplohaplontic.
Reproduction is vegetative by fragmentation, asexual by spore
formation (zoospores) and sexual reproduction by
fusion of two
gametes which may be lsogamous (Spirogyra),
Anisogamous
ECONOMIC IMPORTANCE OF ALGAE:A
number of brown algae (Laminania, Sargassum) are used as food in some
countries.Fucus and Laminaria are rich source of lodine. Laminaria and
Ascophyilum have antibiotic properties.Alginic acid is obtained from Fucus and
Sargassum which is used as emulsions.
BRYOPHYTES:Bryophytes
include various mosses and liverworts; commonly grow in moist shaded areas in
the hills._Bryophytes are also called amphibians of the _ plant . kingdom
because these plants can live in soil but are dependent on water for sexual
reproduction.Plant body is thallus-like and prostrate or erect and attached to
the substratum by unicellular or multicellular rhizoids.They lack true roots,
stem or leaves and may possess root-like, leaf-like or stem-like structures.
The main plant body of the bryophyte is haploid,
produces gametes
and hence is called a gametophyte.The male sex organ
is called antheridium which produce biflagellate antherozoids and the female
sex organ called archegonium is flask- shaped, produces a single egg.
The antherozoids are released into water where they
come in contact
with archegonium and fuses with the egg to produce
the zygote.
Zygotes produce a multicellular body called a
sporophyte, which is not
free-living but attached to the photosynthetic
gametophyte and derives
nourishment from it.Some cells of the sporophyte
undergo reduction division to produce haploid spores, which germinate to
produce gametophyte.The bryophytes are divided into liverworts and mosses.
Liverworts:The liverworts grow usually in moist,
shady habitats.
The plant body of a liverwort is thalloid, the
thallus is dorsiventral and closely appressed to the substrate.Asexual
reproduction in liverworts takes place by fragmentation of thalli or by the
formation of specialized structures called Gemmae which are green,
multicellular, asexual buds, which develop in small receptacles
called gemma cups located on the thalli.The
sporophyte is differentiated into a foot, seta and capsule.After meiosis,
spores are produced within the capsule, the spores germinate to form
free-living gametophytes.
Mosses:The predominant stage of the life cycle of a
moss is the gametophyte which consists of two stages:Protonema stage, which
develops directly from a spore.Leafy stage, which develops from the secondary
protonema as a lateral bud.They are attached to the soil through multicellular
and branched rhizoids.Vegetative reproduction in mosses is by fragmentation and
budding in the secondary protonema.
In sexual reproduction, the sex organs antheridia
and archegonia
produce zygote which develops into a sporophyte,
consisting of a foot,
seta and capsule. Examples of mosses are Funaria,
Polytrichum
PTERIDOPHYTES Found in cool, damp, shady places.
Plant body is a sporophyte which is differentiated into true root, stem and
leaves, possess well-differentiated vascular tissues.The sporophytes bear
sporangia that are subtended by leaf-like appendages called sporophylis, which
may form distinct compact structures called strobili or cones.The sporangia
produce spores by meiosis in spore mother cells and the spores germinate to
give rise to haploid gametophytic structures.The gametophytes bear male and
female sex organs called antheridia and archegonia respectively.Water is
required for transfer of antherozoids to the mouth of archegonium and fusion of
male gamete with the egg present in the archegonium result in the formation of
zygote.Zygote produces a multicellular well-differentiated sporophyte which is
the dominant phase of the pteridophytes.lf all the spores are of similar kinds
such plants are
called homosporous and if the spores are dissimilar
such as micro
and macrospores than itis called heterosporous.The
development of the zygotes into young embryoes takes place within the female
gametophytes.
LET US KNOW WHAT WE HAVE LEARNT?
LEART EXERCISE SOLUTIONS (QUESTIONS 1
TO 6)
Q 1. What is the
basis of classification of Algae?
Ans. The main basis of classification of algae is
the presence or absence of pigments, which gives color to algae:
1. Chlorophyceae contains chlorophyll a and b,
giving it the green colour and the name ‘green algae’.
2. Phaeophyceae contains chlorophyll a and c and
fucoxanthin. The
fucoxanthin gives it the brown colour and hence the
name ‘brown algae’.
3. Rhodophyceae contains chlorophyll a and d and
phycoerythrin. The
phycoerythrin gives the distinct red colour and
hence the name ‘red
algae.
Q 2. When and
where does reduction division take place in the life cycle of a liverwort, a
moss, a fern, a gymnosperm and an angiosperm?
Ans. Liverwort-—In_ liverworts, the main. plant-body
is haploid
(gametophytic). It bears the male and female sex
organs which produce
gametes. These gametes fuse to form a zygote. The
zygote develops on the gametophytic plant-body to form a sporophyte. The
sporophyte is
differentiated into the foot, seta, and capsule.
Many haploid spores are produced as a result of the reduction division taking
place inside the capsule.Moss — in mosses, the primary protonema (developed in
the first stage)develops into the secondary protonema. Both these stages are
haploid or gametophytic. The secondary protonema bears the sex organs which
produce gametes. These gametes fuse to form a zygote. The zygote develops into
a sporophyte. Many spores are formed as a result of the reduction division
taking place in the capsule of this sporophyte.Fern — In ferns, the main
plant-body is sporophytic. Its leaves are known as sporophylls and these bear
the sporangia. Reduction division takes place in these sporangia, thereby
producing many spores.Gymnosperm — In gymnosperms, the main plant-body is
sporophytic. They bear two types of leaves -— microsporophylls and
megasporophylls.Reduction division takes place in the microsporangia present on
the microsporophylls (producing pollen grains) and on the megasporangia present
on the megasporophylls (producing megaspores).
Angiosperm —I|n angiosperms, the main plant-body is
sporophytic and
bears flowers. The male sex organ in the flower is
the stamen, while the female sex organ is the pistil. Reduction division takes
place in the anthers of the stamen (producing haploid pollen grains) and in the
ovary of the pistil(producing eggs).
Q 3. Name three
groups of plants that bear archegonia. Briefly describe the life cycle of any
one of them.
Ans. Archegonium is the female sex organ that
produces the female
gamete or egg. It is present in the life cycles of
bryophytes, pteridophytes,and gymnosperms.Life cycle of a fern (Dryopteris)
Dryopteris is a common fern with pinnately-compound
leaves. The main
plant-body is sporophytic. Many sporangia are borne
on the lower surfaces of its mature leaves. Each sporangium has spore mother
cells which undergo meiosis to produce haploid spores. On maturing, these
spores dehisce and germinate to give rise to a heart-shaped gametophyte called
prothallus.The prothallus bears the male and female sex organs called
antheridia and archegonia respectively. Tne antheridia produce sperms that swim
in water to reach the archegonia. The egg is produced by the archegonia. As a
result of fertilisation, a zygote is formed. The zygote forms an embryo, which
in turn
develops into a new sporophyte. The young plant
comes out of the
archegonium of the parent gametophyte.
Q 4. Mention the
ploidy of the following: protonemal cell of a moss; primary endosperm nucleus
in dicot, leaf cell of a moss; prothallus cell of a fern:gemma cell in
Marchantia; meristem cell of monocot, ovum of a liverwort,and zygote of a fern.
Ans. (a) Protonemal cell of a moss — Haploid
(b) Primary endosperm nucleus in a dicot — Triploid
(c) Leaf cell of a moss — Haploid
(d) Prothallus of a fern — Haploid
(e) Gemma cell in Marchantia — Haploid
(f) Meristem cell of a monocot — Diploid
(g) Ovum of a liverwort — Haploid
(h) Zygote of a fern — Diploid
Q 5. Write a note
on economic importance of algae and gymnosperms.
Ans. Economic importance of algae:
(a) Food source: Many species of marine algae such
as Porphyra, Sargassum, and Laminaria are edible. Chlorella and Spirulina are
rich in proteins. Thus, they are used as food supplements.
(b) Commercial importance: Agar is used in the
preparation of jellies and ice-cream. It is obtained from Gelidium and
Gracilaria. Carrageenin is used as an emulsifier in chocolates, paints, and
toothpastes. It is obtained from the red algae.
(c) Medicines: Many red algae such as Corallina are
used in treating worm infections.
Economic importance of gymnosperms:
(a) Construction purposes: Many conifers such as
pine, cedar, etc., are sources of the soft wood used in construction and
packing.
(b) Medicinal uses: An anticancer drug Taxol is
obtained from Taxus. Many species of Ephedra produce ephedrine, which can be
used in the treatment of asthma and bronchitis.
(c) Food source: The seeds of Pinus gerardiana
(known as chilgoza) are
edible.
(d) Source of resins: Resins are used commercially
for manufacturing
sealing waxes and water-proof paints. A type of
resin known as turpentine is obtained from various species of Pinus.
Q 6. Both
Gymnosperms and Angiosperms bear seeds, then why are they
classified separately?
Ans. Both Gymnosperms and Angiosperms bear seeds,
but they are yet
classified separately, because in case of
gymnosperms, the seeds are naked i.e. the seeds are not produced inside the
fruit but in case of angiosperms,the seeds are covered i.e. the seeds are
enclosed inside the fruit.
A27
RECAPITULATION:
GYMNOSPERMS:Gymnosperms are a group of plants that
produce seeds not enclosed within the ovary or fruit” The seeds are open to the
air and are directly fertilized by
pollination.“Gymnosperm”, from the Greek, gymnos, “naked” and sperma, “seed”.
They develop their seeds on the surface of scales and leaves, which often grow
to form cone or stalk shapes, contrasting in characteristics from the
angiosperms, flowering plants which enclose their seeds within an ovary.The
gymnosperms consist of the conifers, the cycads, the gnetophytes and the
sole extent species of the Gynkgophyta division, the
Gingko biloba.
CHARACTERISTICS OF GYMNOSPERMS:They
do not produce flowers.Seeds are not formed inside a fruit. They are naked.They
are found in colder regions where snowfall occurs.They are perennial or woody,
forming trees or bushes.They are not differentiated into ovary, style and
stigma.Since stigma is absent, they are pollinated directly by the wind.The
male gametophytes produce two gametes, but only one of them is functional.They
form cones with reproductive structures.The seeds contain endosperm that stores
food for the growth and development of the plant.These plants have vascular
tissues which help in the transportation of nutrients and water.Xylem does not
have vessels and the phloem has no companion cells and sieve tubes.The roots
are generally tap roots. Roots in some plants have a fungal
association in the form of mycorrhiza (Pinus), while
in some others (Cycas)small specialised roots called coralloid roots are
associated with N2- fixing cyanobacteria.The stems are branched (Pinus, Cedrus)
or unbranched (Cycas).The leaves may be simple or compound. The leaves in gymnosperms
are well-adapted to withstand extremes of temperature, humidity and wind. In
conifers, the needle-like leaves reduce the surface area. Their thick cuticle
and sunken stomata also help to reduce water loss.
ECONOMIC IMPORTANCE OF GYMNOSPERMS:Seeds
of Pinus gerardiana (chilgoza) are used a food after roasting. Some other
edible gymnosperms plant part are endosperm of Ginkgo, seed kernel of some
Cycas and Gnetum, sago grains from stems of Cycas, etc.Gymnosperms provide
softwood for construction, plywood and paper industry.Branches of gymnosperm
trees are used as fuel food. Saw dust of conifers is used in making plastics
and linoleum.
ANGIOSPERMS:The
angiosperms are vascular seed plants in which the ovule (egg) is fertilized and
develops into a seed in an enclosed in ovary. The ovary itself is usually
enclosed in a flower, that part of the angiospermous plant that contains the
male or female
reproductive organs or both. Fruits are derived from
the maturing floral organs of the angiospermous plant . They occur in a wide
range of habitats. They are also known as flowering plants. Tne pollen grains
and ovules are developed in specialized structures known as flowers while seeds
are enclosed in fruits.
CHARACTERISTICS OF ANGIOSPERMS :Angiosperms have diverse characteristics. The important characteristics of angiosperms are mentioned below:
ECONOMIC IMPORTANCE OF ANGIOSPERMS:It
provides food in form of fruits and seeds. For example:- all cereal grains and
most vegetables, fruits, and nuts are obtained from We get several types of
medicines from these plants.Fibers are obtained from the plants like cotton,
jute etc.
Flowers are used for decoration and also in
religious purposes. The
angiosperms account for most of the photosynthetic
conversion of radiant energy into chemical energy. Angiosperms thus form the
basis for most terrestrial food chains.
ALTERNATION OF GENERATION:Different
plant groups complete their life cycles in different patterns. Angiosperms
complete their life cycle in two phases- a diploid sporophytes and haploid
gametophyte. The two follows each other. This phenomenon is called alternation
of
generation.HAPLONTIC- Saprophytic generation is
represented by only the one-celled zygote. Meiosis in zygote results into
haploid spores to form gametophytes, which is the dominant vegetative phase.
Example- Volvox, Spirogyra etc. DIPLONTIC- Diploid sporophytes is dominant,
independent, photosynthetic plants.The gametophyte is represented by single to
few celled. All seed bearing plants fall under this category.HAPLO-DIPLONTIC-
Both phases are multicellular and intermediate condition is present. It is
present in Bryophytes and Pteridophytes.
LET US KNOW WHAT WE _ HAVE LEARNT!
LET US DO NCERT EXERCISE QUESTIONS 7 to
12
Q.7. What is
heterospory? Briefly comment on its significance. Give two examples.
Ans. Occurrence of two kinds of spores in the same
plant is called as heterospory.Among them the smaller spore is called
microspore and the larger spore is called megaspore. Heterospory first evolved
in pteridophytes.Significance :
(i) Heterospory is associated with the sexual
differentiation of gametophyte a microspore develops into a male gametophyte
whereas a megaspore develops into a female gametophyte.
(ii) In case of pteridophytes heterospores germinate
within the sporangium and the gametophytes are retained inside for variable
periods of time. Hence, germinating gametophyte has better chances of survival.
(iii) Heterospory is the basis of development of
seed habit in higher plants.For example: Selaginella and Salvinia.
Q. 8. Explain
briefly the following terms with suitable examples: -
(i) protonema
(ii) antheridium
(iii) archegonium
(iv) diplontic
(v) sporophyll
(vi) isogamy
Ans. (i) Protonema - It is the first stage in the
life cycle of a moss, developing directly from the spore. It consists of
creeping, green, branched, and often filamentous structures.
(ii) Antheridium —-It is the male sex organ present
in bryophytes and
pteridophytes and is surrounded by a jacket of
sterile cells. It encloses the sperm mother cells, which give rise to the male
gametes.
(iii) Archegonium -It is the female sex organ
present in bryophytes,
pteridophytes, and gymnosperms. In bryophytes and
pteridophytes, it generally has a swollen venter and a tubular neck, and
contains the female gamete called the egg.
(iv) Diplontic —It is the term used for the life
cycles of seed-bearing plants (gymnosperms and angiosperms). In these plants,
the diploid sporophyte is dominant, photosynthetic, and independent. The
gametophyte is represented by a single-celled (or a few-celled) structure.
(Vv) Sporophyll — In pteridophytes, the sporophytic
plant body bears sporangia.These sporangia are subtended by leaf-like appendages
known as sporophylls. In gymnosperms, microsporophylls and megasporophylls are
found. These bear microspores and megaspores respectively.
(vi) Isogamy —It is a type of sexual reproduction
involving the fusion of morphologically-similar gametes. This means that the
gametes are of the same size, but perform different functions. This type of
reproduction is commonly observed in Spirogyra.
Q. 9.
Differentiate between the following: -
(i) red algae and brown aigae
(ii) liverworts and moss
(iii) homosporous and heterosporous pteridophyte
(iv) syngamy and triple fusion
Ans.(i) Red algae and brown algae
Q. 10. How would
you distinguish monocots from dicots?
Ans.MONOCOTYLEDONS DICOTYLEDONS
1. The seeds of these plants have cotyledon. two
cotyledons.
2. The leaves have reticulate veins are parallel.
venation.
3.This group contains adventitious 3. They contain
tap roots
4.Each floral whorlhas three| 4. The flowers are tetramerous or
members. It has closed vascular|pentamerous and the
vascular
bundles and large in number. bundles are organized
in rings.
5. eg. banana, sugarcane, lilies, | 5. eg. Almonds,
pea etc.
Q. 11. Match the
followings (column | with column Il)
Ans.Selaginella Pteridophyte
Q. 12. Describe
the important characteristics of gymnosperms.
Ans. Following are the important characteristics of
gymnosperms:
1. They do not produce flowers.
2. Seeds are not formed inside a fruit. They are
naked.
3. They are found in colder regions where snowfall
occurs.
4. They are perennial or woody, forming trees or
bushes.
5. They are not differentiated into ovary, style and
stigma.
6. Since stigma is absent, they are pollinated
directly by the wind.
7. The male gametophytes produce two gametes, but
only one of them is
functional.
8. They form cones with reproductive structures.
9. The seeds contain endosperm that stores food for
the growth and
development of the plant.
10. These plants have vascular tissues which help in
the transportation of nutrients and water.
11. Xylem does not have vessels and the phloem has
no companion cells and sieve tubes.
12. The roots are generally tap roots. Roots in some
plants have a fungal association in the form of mycorrhiza (Pinus), while in
some others (Cycas) small specialised roots called coralloid roots are
associated with N2- fixing cyanobacteria.
13. The stems are branched (Pinus, Cedrus) or
unbranched (Cycas).
14. The leaves may be simple or compound. The leaves
in gymnosperms are well-adapted to withstand extremes of temperature, humidity
and wind. In conifers, the needle-like leaves reduce the surface area. Their
thick cuticle and sunken stomata also help to reduce water loss.
