NEET Biology Plant Kingdom Important Questions Set 01

These Class 11 NEET Biology important questions on Plant Kingdom give 45 questions with step-by-step answers, arranged as very short, short and long answer types, as asked in school and board examinations. They help NEET aspirants revise the definitions, structures, differences and key terms of the chapter.

Very Short Answer Type Questions

Question 1. What are zoospores?
Answer: Zoospores are flagellated (motile) asexual spores.

Question 2. What is the basis of cytotaxonomy?
Answer: Cytotaxonomy is based on cytological information like chromosome number, structure and behaviour.

Question 3. Name two unicellular algae used as food.
Answer: Chlorella and Spirullina.

Question 4. Who gave the most popular natural system of classification?
Answer: George Bentham and Joseph Dalton Hooker.

Question 5. What is the function of holdfast in brown algae?
Answer: Holdfast attaches the plant to a substratum.

Question 6. Name the sex organ which produces antherozoids in Funaria.
Answer: Antheridium (male sex organ).

Question 7. What are gemmae?
Answer: Gemmae are green, multicellular asexual buds produced by certain bryophytes which on separation grow into a new plant.

Question 8. What are microphylls?
Answer: In some pteridophytes like Selaginella the leaves are small and are known as microphylls.

Question 9. Write down the type of life cycle found in Fucus.
Answer: Diplontic.

Question 10. What is the ploidy of a male gamete present in the pollen grain?
Answer: Haploid.

Short Answer Type Questions

Question 11. Define isogamous and anisogamous reproduction.
Answer: Fusion between two gametes which are similar in size, either flagellated or non-flagellated, is termed as isogamous. Fusion of two gametes dissimilar in size is termed as anisogamous.

Question 12. How algae increases the level of dissolved oxygen in their immediate environment?
Answer: Algae fix at least half of the total carbon dioxide of earth, by the process of photosynthesis. During this process oxygen is released thus, they increase the level of dissolved oxygen in their immediate environment.

Question 13. Define numerical taxonomy.
Answer: Numerical taxonomy is based on all observable characteristics. Number and codes are assigned to all the characters and then data is processed. In this way each character is given equal importance and at the same time hundreds of characters can be considered.

Question 14. Explain how liverworts reproduce asexually.
Answer: Asexual reproduction in liverworts takes place by fragmentation of thalli or by gemmae formation. The gemmae become detached from the body and germinate to form new individuals. In fragmentation the parent body breaks into two or more fragments. Each fragment develops into a thallus.

Question 15. Explain how mosses reproduce sexually.
Answer: During sexual reproduction antherozoids are released into water. When they come in contact with archegonium, an antherozoid fuses with the egg to produce the zygote which develops into a multicellular sporophyte consisting of foot, seta and capsule. The capsule produces spores. Spores are formed after meiosis. These spores germinate to produce gametophyte.

Question 16. Mention the "division" of plant group that is known as non-vascular amphibians of the plant kingdom. Why are they called so?
Answer: Bryophytes. They are called as the non-vascular amphibians of the plant kingdom because they lack vascular bundles and can live in soil but are dependent on water for sexual reproduction.

Question 17. Explain how sexual reproduction occurs in gymnosperms?
Answer: The pollen grains are transferred by air and come in contact with the opening of the ovules. Each pollen germinates and forms pollen tube which reaches the archegonia in the ovules. The pollen tube discharges the male gametes near the mouth of the archegonia where fertilisation takes place. The zygote develops into an embryo and the ovules into seeds.

Question 18. How can we say that embryo sac is haploid?
Answer: Embryo sac formation is preceded by meiosis. A single megaspore mother cell of the nucellus undergoes meiosis to produce four haploid megaspores. Out of four only one functional megaspore develops into the female gametophyte or the embryo sac.

Question 19. What is the difference between pollination and syngamy?
Answer: Pollination is the transfer of pollen grain (immobile structure) from anther to stigma whereas syngamy is the fusion of two gametes to produce the zygote.

Question 20. What is alternation of generation?
Answer: Different plant groups complete their sexual life cycles in different patterns. The diploid sporophyte and the haploid gametophyte follow each other rigidly. The phenomenon is called alternation of generation.

Question 21. Discuss the flagellar number and position of insertion in different classes of algae.

Answer:

Question 22. How is secondary nucleus formed? What is the ploidy of primary endosperm nucleus (PEN)?
Answer: Secondary nucleus is formed by the fusion of two polar nuclei. PEN is a triploid structure as it is product of triple fusion.

Question 23. What is nucellus in gymnosperms?
Answer: Tissue composing the chief part of the young ovule is known as nucellus. The magaspore mother cell is differentiated from one of cell of nucellus.

Question 24. In pteridophytes how the haploid spores are produced?
Answer: In pteridophytes, the dominant phase is a sporophyte which contains sporophylls. The spore mother cells present in the sporangia undergo meiosis to produce haploid spores.

Question 25. Give two general characteristics of rhodophyceae.
Answer: (i) They are called red algae because of the predominance of the red pigment, r-phycoerythrin.
(ii) They are mostly found in marine habitat with greater concentrations found in the warmer areas.

Question 26. Name the algae from which agar is obtained. Give two uses of agar.
Answer: Gelidium and Gracilaria Uses of agar :
(i) To grow microbes
(ii) In preparations of ice-creams and jellies

Question 27. Give two general characteristics of angiosperms.
Answer: (i) Angiosperms are also known as flowering plants and grow in almost every kind of habitats.
(ii) In angiosperms, the pollen grains and ovules are developed in specialised structures called flowers and the seeds are enclosed by fruits.

Question 28. What is the storage food in different classes of algae?
Answer: In green algae, stored food is starch. In brown algae, food is stored as laminarin and mannitol. In red algae, food is stored in the form of floridean starch.

Question 29. Draw a well-labelled diagram of Fucus.
Answer: A well-labelled diagram should show these parts: Air bladder; Frond; Midrib; Holdfast; Fucus.

Question 30. Define microsporangiate and macrosporangiate.
Answer: In gymnosperms, the cones bearing microsporophylls and microsporangia are called as microsporangiate or male strobili. The cones bearing megasporophylls with megasporangia or ovules are called macrosporangiate or female strobili.

Long Answer Type Questions

Question 31. Represent schematically the type of life cycle pattern exhibited by most of the algae.

Answer:

Algae generally exhibit haplontic life cycle.

Me am (2n) y Spores (n) A B Gametogenesis Haplontic

Gametophyte (n)

Question 32. Explain the haplo-diplontic condition in bryophytes and pteridophytes.
Answer: It is an intermediate type of life cycle where both the sporophyte and gametophyte are multicellular and often free-living. Bryophytes and pteridophytes exhibit this pattern. In bryophytes the dominant phase is the independent gametophyte and it alternates with the short-lived multicellular sporophyte totally or partially dependent on the gametophyte for its anchorage and nutrition. In pteridophytes, the dominant phase is represented by the sporophyte which is diploid, independent, photosynthetic vascular plant body. It alternates with multicellular, independent but short-lived haploid gametophyte.

Question 33. (a) Draw a well-labelled diagram of Funaria representing gametophyte and sporophyte.
(b) Explain the sexual reproduction in brown algae.

Answer:

(a) Capsule

Sporophyte Seta

Leaves

Gametophyte Main axis Rhizoids

(b) Sexual reproduction may be isogamous, anisogamous or oogamous. Union of gametes may take place in water or within the oogonium. The gametes are pyriform (pear-shaped) and bear two laterally attached flagella.

Question 34. What are different cells present in the embryo sac? Discuss their fate.
Answer: Each embryo sac has a three-celled egg apparatus – one egg cell and two synergids, three antipodal cells and two polar nuclei. The polar nuclei eventually fuse to produce a diploid secondary nucleus. Fate of the cells : The egg cell fuses with one of the male gametes to form the zygote. The secondary nucleus (2n) fuses with the other male gamete to produce the primary endosperm nucleus. The synergids and the antipodal cells degenerate after fertilisation.

Question 35. Discuss double fertilisation.
Answer: Double fertilisation is an event unique to angiosperms. After the dispersal from the anthers, pollen grains are carried by wind or various other agencies to the stigma of a pistil. The pollen grain germinates on the stigma and the resulting pollen tube grows through the tissues of stigma and style and reach the ovule. The pollen tube enters the embryo sac (female gametophyte) and discharge the male gametes present in the pollen grain. One of the male gametes fuses with the egg cell to form zygote. This is known as syngamy. The other male gamete fuses with the diploid secondary nucleus to produce the triploid primary endosperm nucleus (PEN). This primary endosperm nucleus develops into endosperm which nourishes the developing embryo.

Question 36. (a) Discuss the structure of carpel.
(b) Discuss the post fertilisation development in angiosperms.
Answer: (a) Pistil or the carpel is the female sex organ in a flower. A pistil has three parts – stigma, style and ovary. Stigma is the terminal receptive part of the pistil which functions as landing platform for the pollen grains. Style is elongated narrow stalk that connects the ovary with the stigma. Ovary is the basal swollen part of the pistil. It may have one to several ovules. The number of ovules in an ovary may be one or many. Each ovule has one or two protective envelops called integuments. Enclosed within the integuments is a mass of cells called the nucellus.
(b) The synergids and antipodals degenerate. Ovules develop into seeds and the ovaries develop into fruit.

Question 37. Give five main characteristics of brown algae.
Answer: (i) The members of phaeophyceae are commonly called brown algae. Majority of the brown algae are found in marine habitats.
(ii) They possess the pigment chlorophyll a & c, carotenoids and xanthophyll.
(iii) They vary in colour from olive green to various shades of brown depending upon the amount of the xanthophyll called fucoxanthin.
(iv) They shows great variation of size and form. In Ectocarpus the body is simple branched and filamentous whereas in kelps the body is profusely branched. Kelps may reach a height of 100 metres.
(v) Food is stored as complex carbohydrates which may be laminarin or mannitol.

Question 38. What is the dominant phase of pteridophytes and how is it formed?
Answer: The dominant phase in pteridophyte is a sporophyte.
(i) The sporangia contain sporogenous tissue, where spore mother cells undergo meiosis to produce spores.
(ii) The spores germinate to give rise to inconspicuous, small but multicellular, free living, mostly photosynthetic thalloid gametophytes called prothallus.
(iii) The gametophytes bear male and female sex organs called antheridia and archegonia respectively.
(iv) Sperms are flagellated (antherozoids). They require an external supply of water for swimming to the mouth of archegonium.
(v) Fusion of gametes result in the formation of zygote which develop into embryo. The embryo develops into a multicellular well-differentiated sporophyte.

Question 39. Discuss the economic importance of pteridophytes.
Answer: (a) Soil binding : Pteridophytes bind the soil even along hill slopes. The soil is protected from erosion.
(b) Medicines : An anthelmintic drug is obtained from Dryopteris.
(c) Ornamentals : Ferns are grown as ornamental plants for their delicate and graceful leaves.
(d) Food : Marsilea, a water fern yields starch that constitute a good source of food for certain tribals.
(e) Scouring : Equisetum stems have been used in scouring (cleaning of utensils) and polishing of metals.

Question 40. Discuss the artificial and natural classification systems.

Answer:

Artificial System of Classification

The earliest systems of classification were artificial. For example, classification within the angiosperms were based only on gross superficial morphological characters such as habit, colour, number and shape of leaves etc. Such systems were based mainly on vegetative characters. They separated the closely related species as they were based on a few characteristics. Also equal weightage to vegetative and sexual characteristics were given by the systems but as we know, the vegetative characters are more affected by environment, so this was not acceptable and therefore the natural classification system developed.

Natural System of Classification

Organisms in this system are classified on the basis of natural affinities and consider not only external but also internal features like ultrastructure, anatomy, embryology and phytochemistry. George Bentham and Joseph Dalton Hooker gave such a classification for flowering plants.

Question 41. Discuss phylogenetic classification system, numerical taxonomy, cytotaxonomy and chemotaxonomy.

Answer:

Phylogenetic System of Classification

At present phylogenetic classification systems are acceptable which are based on evolutionary relationships between the various organisms, assuming that organisms belonging to the same taxa have common ancestor.

Information from many other sources help to resolve difficulties in classification.

Numerical Taxonomy : It is based on all observable characteristics, carried out using computers. Number and codes are assigned to all the characters and then data is processed. In this way each character is given equal importance and at the same time hundreds of characters can be considered.

Cytotaxonomy : It is based on cytological informations like chromosome number, structure, behaviour.

Chemotaxonomy : It is based on the chemical constituents of the plant.

Question 42. (a) What are the functions of following structures in algae?
(i) Holdfast
(ii) Frond
(iii) Air bladder
(b) Mention the pigments and reserve food material present in the algae possessing the above mentioned structures.

Answer:

(a) (i) Holdfast helps in attaching the plant body to a substratum.

(ii) Frond is leaf-like structure meant for photosynthesis.

(iii) Air bladder provide buoyancy.

(b) The plant body of brown algae is often differentiated into holdfast, stipe and frond. They possess the pigment chlorophyll a & c, carotenoids and xanthophyll.

Reserve food material is laminarin or mannitol.

Question 43. Discuss the major pigments and cell wall composition of different classes of algae.

Answer:

Chlorophyceae : Contains pigments, chlorophyll a & b. Green algae usually have a rigid cell wall made of an inner layer of cellulose and an outer layer of pectose.

Phaeophyceae : Contains pigments, chlorophyll a & c, carotenoids and xanthophylls. The vegetative cells have a cellulosic wall usually covered on the outside by a gelatinous coating of algin.

Rhodophyceae : Pigments present are chlorophyll a & d, phycoerythrin. Cell wall is made up of cellulose and poly sulphate esters.

Question 44. Discuss the economic importance of bryophytes.

Answer:

(a) Prevention of soil erosion : Bryophytes, especially mosses, form dense mats over the soil and prevent soil erosion against falling rains.

(b) Soil formation : Mosses are an important link in plant succession on rocky areas. They take part in building soil in rock crevices formed by lichens. Growth of Sphagnum (Bog moss) ultimately fills ponds and lakes with soil.
(c) Water retention : Dry Sphagnum has great water absorbing capacity. This characteristic is employed by garderners to keep seedlings and cut plants moist during transportation and propagation. Sphagnum moss was used in place of absorbent cotton, so is also called cotton moss.

(d) Peat : Sphagnum often grows in acidic marshes. The older dead parts of moss and other marshy plants got slowly carbonised, compressed and fossilised over thousands of years and have produced a dark spongy mass called peat. Peat is dried, compressed and cut to form blocks. The peat blocks are used as fuel. Peat is also a good manure. It overcomes soil alkalinity and increases its water retention as well as aeration.

(e) Other uses : In rocky and ice cold areas mosses are a good source of food for certain animals like birds. A decoction of Polytrichum commune was employed in removing kidney stones.

Question 45. Represent schematically the life cycle of a gymnosperm.

Answer:

Sporophyte (2n) Seed (2n) Female cone Male cone

Microsporophylls Mega- Embryo (2n) Sporophytic sporophylls (2n) phase Micro- sporangia Megasporangia (ovules) Zygote (2n) Microspore Fusion mother cell (2n) Gametophytic Megaspore
(n) generation mother cell (2n) Male Me gametes (n) ios is Meiosis

Megaspores (n) Archegonia Female gametophyte (n)

Life Cycle of a Gymnosperm