Plant Kingdom

What to remember

• Classification has moved from artificial systems (based on a few characters, such as the androecium) to natural systems (based on overall affinities) to phylogenetic systems (based on evolutionary relationships and a common ancestor).
• Algae are simple, thalloid, chlorophyll-bearing and mostly aquatic. Chlorophyceae are green (chlorophyll a, b; starch), Phaeophyceae are brown (fucoxanthin; mannitol, laminarin) and Rhodophyceae are red (phycoerythrin; floridean starch).
• Bryophytes have a dominant haploid gametophyte and need water for fertilisation. Pteridophytes are the first vascular plants and have a dominant sporophyte with a free-living prothallus. Gymnosperms have naked seeds. Angiosperms have seeds inside fruits.
• Life cycles are of three types: haplontic (dominant gametophyte, for example Volvox, Spirogyra), diplontic (dominant sporophyte, for example gymnosperms, angiosperms, Fucus) and haplo-diplontic (both phases multicellular, for example bryophytes, pteridophytes, Ectocarpus, kelps).

Basis of classification

Early systems were artificial. They used only a few vegetative or sexual characters. Linnaeus used the androecium (stamen) structure to group flowering plants. Such systems separated closely related species and grouped unrelated ones together.

Natural systems use many characters together: external form, internal structure (anatomy), embryology and plant chemistry. They show natural affinities between organisms.

Phylogenetic systems use evolutionary relationships. They assume that organisms belonging to the same taxon have a common ancestor.

Modern tools add more data to classification.

The Plant Kingdom includes algae, bryophytes, pteridophytes, gymnosperms and angiosperms.

Algae

Algae are chlorophyll-bearing, simple, thalloid and autotrophic organisms. Most are aquatic, in fresh water and in the sea. Some live on moist stones, soil and wood. Some live in association with fungi (lichens) and with animals (for example sponges).

The form varies a great deal: unicellular (Chlamydomonas), colonial (Volvox), filamentous (Ulothrix, Spirogyra) and massive (kelps, which can grow to a very large size).

Reproduction is of three kinds:

• Vegetative: fragmentation. Each fragment grows into a new thallus.
• Asexual: flagellated zoospores formed in zoosporangia.
• Sexual: fusion of two gametes. It may be isogamous, anisogamous or oogamous.

Economic importance of algae:

• Algae together fix about half of the total carbon dioxide fixed on Earth by photosynthesis. They are the primary producers of aquatic food chains. They increase the dissolved oxygen of their environment.
• Porphyra, Laminaria and Sargassum are used as food.
• Hydrocolloids: algin from brown algae and carrageen from red algae are used commercially.
• Agar is obtained from Gelidium and Gracilaria. It is used to grow microbes and to make ice-creams and jellies.
• Chlorella and Spirulina are unicellular algae rich in protein. They are used as food supplements, even by space travellers.

Chlorophyceae, Phaeophyceae and Rhodophyceae

Points about each class:

• Green algae can be unicellular, colonial or filamentous. Reproduction is vegetative (fragmentation), asexual (flagellated zoospores) or sexual (isogamous, anisogamous or oogamous).
• Brown algae range from simple branched filaments (Ectocarpus) to large plants (kelps). The plant body has a holdfast, a stalk-like stipe and a leaf-like photosynthetic frond. Vegetative reproduction is by fragmentation. Asexual reproduction is by pear-shaped biflagellate zoospores with two unequal, laterally attached flagella. Sexual reproduction may be isogamous, anisogamous or oogamous.
• Red algae are red because of the pigment r-phycoerythrin. Most are marine, especially in warmer areas. Vegetative reproduction is by fragmentation. Asexual reproduction is by non-motile spores. Sexual reproduction is oogamous, with complex post-fertilisation changes.

Bryophytes

Bryophytes include liverworts and mosses. They are called the amphibians of the plant kingdom. They live in soil but depend on water for sexual reproduction. They grow in damp, humid and shaded places.

The plant body is thallus-like, prostrate or erect, and is attached to the substratum by unicellular or multicellular rhizoids. There are no true roots, stem or leaves. Only root-like, leaf-like or stem-like structures are present.

• The main plant body is haploid. It is the gametophyte, and it produces gametes.
• The male sex organ is the antheridium. It produces biflagellate antherozoids.
• The female sex organ is the archegonium. It is flask-shaped and produces a single egg.
• Antherozoids swim in water to the archegonium. Fusion gives the zygote.
• The zygote develops into a multicellular sporophyte. It is not free-living. It is attached to the gametophyte and takes nourishment from it.
• Some cells of the sporophyte undergo meiosis and form haploid spores. A spore germinates into a gametophyte.

Importance of bryophytes:

• Sphagnum gives peat, which is used as fuel. It holds a lot of water, so it is used as packing material for transporting living plants.
• Mosses and lichens are the first colonisers of rocks. They decompose rock and make a substratum for higher plants.
• Mosses form dense mats on soil. They reduce the impact of falling rain and prevent soil erosion.

Pteridophytes

Pteridophytes include horsetails and ferns. They are the first terrestrial plants to have vascular tissues, xylem and phloem. They grow in cool, damp and shady places. They are used for medicine, as soil binders and as ornamentals.

• The main plant body is the sporophyte. It is differentiated into true root, stem and leaves.
• Leaves are small (microphylls), as in Selaginella, or large (macrophylls), as in ferns.
• Sporangia are borne on leaf-like appendages called sporophylls. In some plants (Selaginella, Equisetum) sporophylls form compact structures called strobili or cones.
• Spore mother cells in the sporangia divide by meiosis to make spores.
• A spore germinates into a small, multicellular, free-living, mostly photosynthetic, thalloid gametophyte called the prothallus. It needs cool, damp, shady places because fertilisation needs water.
• The gametophyte bears antheridia and archegonia. Water is needed to carry the male gametes to the archegonium. The zygote develops into the sporophyte.

Most pteridophytes make one kind of spore, so they are homosporous. Selaginella and Salvinia make two kinds, small microspores and large megaspores, so they are heterosporous. Microspores give male gametophytes and megaspores give female gametophytes. The female gametophyte is retained on the parent sporophyte, and the young embryo develops inside it. This is a precursor to the seed habit.

Gymnosperms

In gymnosperms the ovules are not enclosed by an ovary wall. They are exposed before and after fertilisation, so the seeds are naked. The group includes medium-sized and tall trees and shrubs. Sequoia (giant redwood) is among the tallest tree species.

Vegetative features:

• Roots are generally tap roots.
• Pinus roots have a fungal association called mycorrhiza. Cycas has small specialised coralloid roots associated with nitrogen-fixing cyanobacteria.
• Stems are unbranched (Cycas) or branched (Pinus, Cedrus).
• Leaves may be simple or compound. Cycas has pinnate leaves. Conifer leaves are needle-like, with a thick cuticle and sunken stomata. These features reduce water loss.

Reproductive features:

• Gymnosperms are heterosporous. They make haploid microspores and megaspores in sporangia borne on sporophylls. The sporophylls are arranged spirally on an axis to form strobili or cones.
• Male (microsporangiate) strobili bear microsporophylls with microsporangia. Microspores develop into a highly reduced male gametophyte, the pollen grain.
• Female (macrosporangiate) strobili bear megasporophylls with ovules (megasporangia). Male and female cones are on the same tree in Pinus and on different trees in Cycas.
• The megaspore mother cell forms in the nucellus. The nucellus with its protective envelopes is called the ovule. The megaspore mother cell divides by meiosis into four megaspores. One develops into a multicellular female gametophyte with two or more archegonia. The female gametophyte stays inside the megasporangium.
• Pollen grains are carried by air currents (wind pollination) to the opening of the ovule. A pollen tube carries male gametes to the archegonia.
• After fertilisation the zygote becomes the embryo and the ovule becomes the seed.

Angiosperms in brief

Angiosperms are flowering plants. Pollen grains and ovules develop in flowers. The seeds are enclosed in fruits. They range from the tiny Wolffia to tall Eucalyptus trees. They are divided into dicotyledons and monocotyledons.

• The stamen (male) has a filament and an anther. Pollen grains are formed in the anther. The pollen grain is the male gametophyte.
• The pistil (female) has a stigma, style and ovary. The ovules are inside the ovary.
• In the ovule, the megaspore mother cell divides by meiosis into four megaspores. One is functional and forms the embryo sac, which is the female gametophyte. It has 7 cells and 8 nuclei.
• Double fertilisation: one male gamete fuses with the egg to form the zygote. The other fuses with the two polar nuclei to form the triploid primary endosperm nucleus, which becomes the endosperm.
• The ovule becomes the seed and the ovary becomes the fruit.

Plant life cycles and alternation of generations

In sexual reproduction, a haploid gametophyte phase alternates with a diploid sporophyte phase. This is alternation of generations. Meiosis returns the cells to the haploid state, and fertilisation restores the diploid state. Plants differ in which phase is dominant.

Flow in a haplontic cycle: gametophyte (n) → gametes → zygote (2n) → meiosis → spores (n) → gametophyte (n).

Flow in a diplontic cycle: sporophyte (2n) → meiosis → spores (n) → tiny gametophyte (n) → gametes → zygote (2n) → sporophyte (2n).

NEET traps

• 1. Linnaeus's system is artificial, not natural. It used the androecium.
• 2. Brown algae store mannitol and laminarin. Red algae store floridean starch. Green algae store starch.
• 3. Chlorophyll c belongs to brown algae. Chlorophyll d belongs to red algae. Chlorophyll b belongs to green algae.
• 4. Red algae have no flagella. Brown algae have two unequal lateral flagella. Green algae have 2–8 equal apical flagella.
• 5. The dominant plant body is the gametophyte in bryophytes but the sporophyte in pteridophytes. In both groups the cycle is haplo-diplontic.
• 6. The bryophyte sporophyte is not free-living. The pteridophyte prothallus is free-living.
• 7. Psilopsida is Psilotum, Lycopsida is Selaginella and Lycopodium, Sphenopsida is Equisetum, and Pteropsida is the ferns.
• 8. Cycas has coralloid roots with cyanobacteria. Pinus has mycorrhiza with fungi.
• 9. Fucus is an alga but its cycle is diplontic, not haplontic.
• 10. Sphagnum is a moss, not a liverwort. Marchantia is a liverwort and forms gemmae.

One-liners

• 1. Numerical taxonomy uses coded characters and computers, giving equal weight to all characters.
• 2. Cytotaxonomy uses chromosome data. Chemotaxonomy uses chemical constituents.
• 3. Algae fix about half of the carbon dioxide fixed on Earth.
• 4. Agar comes from Gelidium and Gracilaria. Algin comes from brown algae. Carrageen comes from red algae.
• 5. Chlorella and Spirulina are protein-rich food supplements.
• 6. In oogamy the female gamete is large and non-motile.
• 7. The brown algal body has holdfast, stipe and frond.
• 8. Red algae contain r-phycoerythrin.
• 9. Bryophytes are the amphibians of the plant kingdom.
• 10. Gemmae are formed in gemma cups of liverworts.
• 11. The moss life cycle has a protonema stage and a leafy stage.
• 12. Sphagnum gives peat and is a good packing material because it holds water.
• 13. Pteridophytes are the first plants with xylem and phloem.
• 14. Selaginella and Salvinia are heterosporous pteridophytes.
• 15. A gymnosperm female gametophyte is retained inside the ovule, and pollination is by wind.

Practice questions

1. Linnaeus grouped flowering plants mainly by the structure of the androecium. This is an example of which type of classification?

   1. Numerical taxonomy
   2. Artificial system
   3. Natural system
   4. Phylogenetic system
   Answer

   B. Artificial system

   It used only a few characters such as stamens, so it is an artificial system.

2. Which approach gives equal importance to all characters and uses computers to process coded data?

   1. Cytotaxonomy
   2. Chemotaxonomy
   3. Numerical taxonomy
   4. Phylogenetic system
   Answer

   C. Numerical taxonomy

   Numerical taxonomy codes all characters and processes them by computer.

3. Chromosome number, structure and behaviour are used in which branch of taxonomy?

   1. Cytotaxonomy
   2. Chemotaxonomy
   3. Artificial classification
   4. Numerical taxonomy
   Answer

   A. Cytotaxonomy

   Cytotaxonomy uses cell information, mainly chromosomes.

4. The characteristic xanthophyll pigment of brown algae is

   1. chlorophyll b
   2. phycoerythrin
   3. chlorophyll d
   4. fucoxanthin
   Answer

   D. fucoxanthin

   Brown algae have chlorophyll a, c and fucoxanthin.

5. Carrageen, a commercially used hydrocolloid, is obtained from

   1. brown algae
   2. green algae
   3. red algae
   4. bryophytes
   Answer

   C. red algae

   Algin comes from brown algae and carrageen from red algae.

6. The reserve food of red algae is

   1. starch with pyrenoids
   2. laminarin
   3. mannitol
   4. floridean starch
   Answer

   D. floridean starch

   Red algae store floridean starch, similar to amylopectin and glycogen.

7. Brown algae have flagella that are

   1. two, unequal and lateral
   2. two to eight, equal and apical
   3. four, equal and apical
   4. absent
   Answer

   A. two, unequal and lateral

   Brown algal zoospores have two unequal, laterally attached flagella.

8. Which group is called the amphibians of the plant kingdom?

   1. Pteridophytes
   2. Bryophytes
   3. Gymnosperms
   4. Algae
   Answer

   B. Bryophytes

   Bryophytes live on land but need water for fertilisation.

9. Gemma cups are present on the thallus of

   1. Polytrichum
   2. Funaria
   3. Marchantia
   4. Sphagnum
   Answer

   C. Marchantia

   Marchantia is a liverwort and forms gemmae in gemma cups.

10. The first stage of the gametophyte in a moss, developing directly from a spore, is the

    1. protonema
    2. gemma
    3. leafy stage
    4. prothallus
    Answer

    A. protonema

    A moss spore forms a creeping, filamentous protonema first.

11. The first terrestrial plants to possess xylem and phloem are the

    1. liverworts
    2. pteridophytes
    3. algae
    4. bryophytes
    Answer

    B. pteridophytes

    Pteridophytes are the first vascular plants.

12. Which pair of pteridophytes is heterosporous?

    1. Equisetum and Adiantum
    2. Lycopodium and Psilotum
    3. Dryopteris and Pteris
    4. Selaginella and Salvinia
    Answer

    D. Selaginella and Salvinia

    Selaginella and Salvinia make microspores and megaspores.

13. Psilotum belongs to the class

    1. Sphenopsida
    2. Psilopsida
    3. Lycopsida
    4. Pteropsida
    Answer

    B. Psilopsida

    Psilopsida is represented by Psilotum.

14. Which of the following has a haplontic life cycle?

    1. Spirogyra
    2. Fucus
    3. Funaria
    4. Pinus
    Answer

    A. Spirogyra

    Spirogyra has a dominant haploid gametophyte and a one-celled zygote.

15. In angiosperms, the primary endosperm nucleus is

    1. tetraploid
    2. diploid
    3. triploid
    4. haploid
    Answer

    C. triploid

    A male gamete fuses with two polar nuclei to form a triploid nucleus.

16. Coralloid roots of Cycas are associated with

    1. mycorrhizal fungi
    2. nematodes
    3. nitrifying bacteria
    4. nitrogen-fixing cyanobacteria
    Answer

    D. nitrogen-fixing cyanobacteria

    Cycas coralloid roots host cyanobacteria; Pinus has mycorrhiza.

17. Given below are two statements: Statement I: Chlamydomonas shows isogamy with flagellated gametes. Statement II: The gametes of Spirogyra are flagellated.

    1. Statement I is correct but Statement II is incorrect
    2. Both Statement I and Statement II are correct
    3. Both Statement I and Statement II are incorrect
    4. Statement I is incorrect but Statement II is correct
    Answer

    A. Statement I is correct but Statement II is incorrect

    Spirogyra gametes are non-flagellated.

18. Given below are two statements: Statement I: Red algae store mannitol and laminarin. Statement II: The cell wall of brown algae has a gelatinous coating of algin.

    1. Both Statement I and Statement II are correct
    2. Both Statement I and Statement II are incorrect
    3. Statement I is correct but Statement II is incorrect
    4. Statement I is incorrect but Statement II is correct
    Answer

    D. Statement I is incorrect but Statement II is correct

    Mannitol and laminarin are stored by brown algae, not red algae.

19. Given below are two statements: Statement I: The sporophyte of a bryophyte is free-living. Statement II: The prothallus of a pteridophyte is free-living.

    1. Both Statement I and Statement II are correct
    2. Both Statement I and Statement II are incorrect
    3. Statement I is incorrect but Statement II is correct
    4. Statement I is correct but Statement II is incorrect
    Answer

    C. Statement I is incorrect but Statement II is correct

    Bryophyte sporophytes depend on the gametophyte; the prothallus is free-living.

20. Given below are two statements: Statement I: Sphagnum provides peat that is used as fuel. Statement II: Sphagnum is used as packing material for living plants because it holds water.

    1. Both Statement I and Statement II are incorrect
    2. Both Statement I and Statement II are correct
    3. Statement I is correct but Statement II is incorrect
    4. Statement I is incorrect but Statement II is correct
    Answer

    B. Both Statement I and Statement II are correct

    Both are uses of Sphagnum.

21. Which of the following statements are correct? 1. The sporophyte of a moss is differentiated into foot, seta and capsule. 2. Protonema is the sporophyte stage of a moss. 3. Gemma cups occur on liverwort thalli.

    1. 1 and 2 only
    2. 1 and 3 only
    3. 2 and 3 only
    4. 1, 2 and 3
    Answer

    B. 1 and 3 only

    Protonema is a haploid gametophyte stage.

22. Which of the following statements are correct? 1. Gymnosperms are heterosporous. 2. The ovules of gymnosperms are enclosed in an ovary. 3. The pollen grain is a highly reduced male gametophyte.

    1. 1 and 3 only
    2. 1 and 2 only
    3. 2 and 3 only
    4. 1, 2 and 3
    Answer

    A. 1 and 3 only

    Gymnosperm ovules are naked, not enclosed by an ovary.

23. Given below are two statements: Statement I: In a diplontic life cycle the dominant phase is the diploid sporophyte. Statement II: Fucus has a haplontic life cycle.

    1. Both Statement I and Statement II are correct
    2. Both Statement I and Statement II are incorrect
    3. Statement I is incorrect but Statement II is correct
    4. Statement I is correct but Statement II is incorrect
    Answer

    D. Statement I is correct but Statement II is incorrect

    Fucus is diplontic.

24. Given below are two statements: Statement I: Cytotaxonomy uses chemical constituents of plants. Statement II: Numerical taxonomy gives equal weight to all characters.

    1. Both Statement I and Statement II are correct
    2. Both Statement I and Statement II are incorrect
    3. Statement I is incorrect but Statement II is correct
    4. Statement I is correct but Statement II is incorrect
    Answer

    C. Statement I is incorrect but Statement II is correct

    Chemical constituents are used in chemotaxonomy.

25. Which of the following statements are correct? 1. Double fertilisation produces a triploid primary endosperm nucleus. 2. The embryo sac of an angiosperm has 7 cells and 8 nuclei. 3. The pollen grain is the female gametophyte.

    1. 1 and 3 only
    2. 2 and 3 only
    3. 1 and 2 only
    4. 1, 2 and 3
    Answer

    C. 1 and 2 only

    The pollen grain is the male gametophyte.

26. Given below are two statements: Statement I: The prothallus of a pteridophyte is multicellular, mostly photosynthetic and needs water for fertilisation. Statement II: In Selaginella the female gametophyte is retained on the parent sporophyte and the embryo develops inside it.

    1. Both Statement I and Statement II are incorrect
    2. Both Statement I and Statement II are correct
    3. Statement I is correct but Statement II is incorrect
    4. Statement I is incorrect but Statement II is correct
    Answer

    B. Both Statement I and Statement II are correct

    Both are correct and the second is a precursor to the seed habit.

27. Assertion (A): Sphagnum is used to pack living plants for transport. Reason (R): Sphagnum can hold a large quantity of water.

    1. Both A and R are true and R is the correct explanation of A
    2. Both A and R are true but R is not the correct explanation of A
    3. A is true but R is false
    4. A is false but R is true
    Answer

    A. Both A and R are true and R is the correct explanation of A

    Water-holding capacity keeps the plants moist.

28. Assertion (A): Gymnosperm seeds are called naked. Reason (R): The ovules of gymnosperms are not enclosed by an ovary wall.

    1. Both A and R are true but R is not the correct explanation of A
    2. A is true but R is false
    3. A is false but R is true
    4. Both A and R are true and R is the correct explanation of A
    Answer

    D. Both A and R are true and R is the correct explanation of A

    Exposed ovules give seeds with no covering.

29. Assertion (A): Cycas has coralloid roots. Reason (R): The roots of Pinus form mycorrhiza.

    1. Both A and R are true and R is the correct explanation of A
    2. A is true but R is false
    3. A is false but R is true
    4. Both A and R are true but R is not the correct explanation of A
    Answer

    D. Both A and R are true but R is not the correct explanation of A

    Both are true but unrelated.

30. Assertion (A): The moss sporophyte is not free-living. Reason (R): It remains attached to the gametophyte and takes nourishment from it.

    1. Both A and R are true but R is not the correct explanation of A
    2. A is true but R is false
    3. Both A and R are true and R is the correct explanation of A
    4. A is false but R is true
    Answer

    C. Both A and R are true and R is the correct explanation of A

    Dependence on the gametophyte means it cannot live independently.

31. Assertion (A): Fucus shows a diplontic life cycle. Reason (R): Its dominant phase is the haploid gametophyte.

    1. Both A and R are true and R is the correct explanation of A
    2. A is true but R is false
    3. Both A and R are true but R is not the correct explanation of A
    4. A is false but R is true
    Answer

    B. A is true but R is false

    In Fucus the diploid sporophyte dominates.

32. Assertion (A): Chlorella is a multicellular marine alga used as food by space travellers. Reason (R): Chlorella is rich in protein.

    1. A is false but R is true
    2. Both A and R are true and R is the correct explanation of A
    3. Both A and R are true but R is not the correct explanation of A
    4. A is true but R is false
    Answer

    A. A is false but R is true

    Chlorella is unicellular; it is protein-rich.

33. Match List I with List II. List I: a. Volvox b. Fucus c. Porphyra d. Gelidium List II: i. Brown alga with oogamous reproduction ii. Source of agar iii. Red alga used as food iv. Colonial green alga with oogamy

    1. a-iv, b-i, c-ii, d-iii
    2. a-i, b-iv, c-iii, d-ii
    3. a-iv, b-i, c-iii, d-ii
    4. a-iv, b-iii, c-i, d-ii
    Answer

    C. a-iv, b-i, c-iii, d-ii

    Volvox is green and oogamous; Fucus is brown; Porphyra is eaten; Gelidium gives agar.

34. Match List I with List II. List I: a. Psilopsida b. Lycopsida c. Sphenopsida d. Pteropsida List II: i. Equisetum ii. Adiantum iii. Psilotum iv. Selaginella

    1. a-iii, b-iv, c-ii, d-i
    2. a-iii, b-iv, c-i, d-ii
    3. a-iii, b-i, c-iv, d-ii
    4. a-iv, b-iii, c-i, d-ii
    Answer

    B. a-iii, b-iv, c-i, d-ii

    Psilotum, Selaginella, Equisetum and Adiantum respectively.

35. Match List I with List II. List I: a. Spirogyra b. Pinus c. Funaria d. Dryopteris List II: i. Diplontic ii. Haplontic iii. Haplo-diplontic with dominant gametophyte iv. Haplo-diplontic with dominant sporophyte

    1. a-ii, b-iii, c-i, d-iv
    2. a-ii, b-i, c-iv, d-iii
    3. a-i, b-ii, c-iii, d-iv
    4. a-ii, b-i, c-iii, d-iv
    Answer

    D. a-ii, b-i, c-iii, d-iv

    Spirogyra is haplontic, Pinus diplontic, Funaria gametophyte-dominant, Dryopteris sporophyte-dominant.

36. Match List I with List II. List I: a. Gemma cup b. Protonema c. Peat d. Capsule List II: i. Early stage of a moss gametophyte ii. Asexual structure of liverworts iii. Obtained from Sphagnum iv. Part of the sporophyte that makes spores

    1. a-ii, b-i, c-iii, d-iv
    2. a-i, b-ii, c-iii, d-iv
    3. a-ii, b-i, c-iv, d-iii
    4. a-ii, b-iii, c-i, d-iv
    Answer

    A. a-ii, b-i, c-iii, d-iv

    Gemma cups are liverwort structures; protonema is a moss stage; peat from Sphagnum; spores form in the capsule.

37. Match List I with List II. List I: a. Coralloid roots b. Mycorrhiza c. Microsporophylls with microsporangia d. Nucellus with its envelopes List II: i. Pinus roots ii. Ovule iii. Cycas iv. Male strobilus

    1. a-iii, b-i, c-ii, d-iv
    2. a-iii, b-iv, c-i, d-ii
    3. a-i, b-iii, c-iv, d-ii
    4. a-iii, b-i, c-iv, d-ii
    Answer

    D. a-iii, b-i, c-iv, d-ii

    Coralloid roots are in Cycas; mycorrhiza in Pinus; male strobilus; ovule.

38. Match List I with List II. List I: a. Numerical taxonomy b. Cytotaxonomy c. Chemotaxonomy d. Artificial system List II: i. Chromosome number ii. Plant chemicals iii. Coded characters processed by computer iv. Androecium structure

    1. a-iii, b-i, c-ii, d-iv
    2. a-i, b-iii, c-ii, d-iv
    3. a-iii, b-ii, c-i, d-iv
    4. a-iii, b-i, c-iv, d-ii
    Answer

    A. a-iii, b-i, c-ii, d-iv

    Each approach uses the listed kind of data.

39. A seaweed is olive-brown, has a holdfast, a stipe and a leaf-like frond, and stores mannitol. It belongs to

    1. Chlorophyceae
    2. Phaeophyceae
    3. Rhodophyceae
    4. Bryophyta
    Answer

    B. Phaeophyceae

    Holdfast, stipe, frond and mannitol indicate brown algae.

40. A plant has a dominant free-living sporophyte with xylem and phloem and a small, free-living, photosynthetic thalloid gametophyte. It is a

    1. bryophyte
    2. green alga
    3. pteridophyte
    4. gymnosperm
    Answer

    C. pteridophyte

    A free-living prothallus with a vascular sporophyte is typical of pteridophytes.

41. In a plant the zygote divides by meiosis to form haploid spores, and no free-living sporophyte is present. The life cycle is

    1. haplo-diplontic with dominant gametophyte
    2. diplontic
    3. haplo-diplontic with dominant sporophyte
    4. haplontic
    Answer

    D. haplontic

    Only the zygote is diploid, so the cycle is haplontic.

42. In some pteridophytes the female gametophyte stays on the parent sporophyte and the embryo forms inside it. This event is regarded as

    1. the origin of vascular tissue
    2. a precursor to the seed habit
    3. a method of vegetative propagation
    4. a feature of homospory
    Answer

    B. a precursor to the seed habit

    Retention of the megaspore and embryo development inside is the step towards seeds.

43. A megaspore mother cell in a Pinus ovule has 24 chromosomes. The megaspores formed from it will be

    1. four, each with 12 chromosomes
    2. four, each with 24 chromosomes
    3. two, each with 24 chromosomes
    4. two, each with 12 chromosomes
    Answer

    A. four, each with 12 chromosomes

    Meiosis gives four haploid cells with half the chromosome number.

44. The egg cell of an angiosperm has 10 chromosomes. The primary endosperm nucleus will have

    1. 10 chromosomes
    2. 40 chromosomes
    3. 30 chromosomes
    4. 20 chromosomes
    Answer

    C. 30 chromosomes

    It is triploid (3n) = 3 x 10 = 30.

45. A forest soil patch is covered with dense moss mats. The main benefit of this cover is

    1. formation of vascular tissue
    2. reduced soil erosion
    3. production of seeds
    4. increased nitrogen fixation by coralloid roots
    Answer

    B. reduced soil erosion

    Moss mats reduce the impact of falling rain and prevent soil erosion.