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Q1. Define the following terms: 1. Isogamous fusion 2. Anisogamous fusion 3. Oogamous fusion

Solution

1. Isogamous fusion: Fusion between two gametes of similar size is called isogamous fusion.   2. Anisogamous fusion: Fusion between two gametes which are dissimilar in size is called anisogamous fusion.   3. Oogamous fusion: Fusion between one large, non-motile female gamete and a smaller, motile male gamete is called oogamous fusion.

Q2. Draw a labelled diagram of the lifecycle of an angiosperm.  

Solution

Lifecycle of an angiosperm:        

Q3. What are sporophylls?

Solution

Sporophylls are leaf-like appendages in pteridophytes which bear sporangia.

Q4. What is anisogamous fusion?

Solution

Anisogamous fusion is the fusion between two gametes which are dissimilar in size.

Q5. Name the process by which haploid spores are produced by the sporophyte.

Solution

Meiosis

Q6. Name an alga which shows the diplontic life cycle.

Solution

Fucus

Q7. Give any two examples of pteridophytes in which sporophylls are in the form of strobili.  

Solution

Selaginella, Equisetum  

Q8. State the uses of algae

Solution

Uses of algae:

Algae help to increase the level of dissolved oxygen in their immediate environment.

Species of algae such as Porphyra, Laminaria and Sargassum are used as food.

Hydrocolloids produced by algin and carrageen are used commercially.

Commercial product agar is obtained from certain species of algae.

Examples: Gelidium and Gracilaria

Agar is used in the preparation of ice creams and jellies. It is also used to grow microbes in laboratories.

Species such as Chlorella and Spirulina are rich in proteins and thus used as food supplements.

Q9. State the dominant phase in the life cycle of fern.

Solution

The sporophytic phase is the dominant phase in the life cycle of fern.

Q10. Which plant group produces spores and embryos but lacks vascular tissues and seeds? 

Solution

Bryophytes consist of a thalloid body and are attached by hair-like structures called rhizoids. These lack vascular tissue and require water at the time of fertilisation. The haploid gametophyte (formation of spores for sexual reproduction) alternates with the diploid sporophyte (formation of spores for asexual reproduction). 

Q11. Name the dominant phase in a plant with a haplontic life cycle.

Solution

The gametophyte is the dominant phase in a plant with a haplontic life cycle.

Q12. State any two important features of dicotyledons.

Solution

Important features of dicotyledons:

Seeds of dicotyledons show two cotyledons.

Leaves of dicotyledons show reticulate venation.

Vascular bundles are arranged in concentric circles.

Q13. What are microsporangia or male strobili?

Solution

Microsporangia are the strobili which bear microsporophylls and microsporangia in gymnosperms.

Q14. What are macrosporangia or female strobili?  

Solution

Macrosporangia are cones which bear megasporophylls containing ovules or megasporangia in gymnosperms.  

Q15. State any one feature of conifers which helps to reduce water loss.

Solution

Presence of sunken stomata.

Q16. Write the name of the species of moss which provides peat?

Solution

Sphagnum 

Q17. In plants, haploid as well as diploid cells undergo mitosis. Hence, during the life cycle of a sexually reproducing plant, there is an alternation of generation between gametophyte and sporophyte.

Name the dominant phase seen in the life cycle of gymnosperms.

Name three types of life cycles shown by the plants.

What is the difference between the life cycles of bryophytes and pteridophytes?

What value do you learn from the life cycles of plants?

Solution

Sporophyte is the dominant phase seen in the life cycle of gymnosperms.

The three types of life cycles shown by the plants are haplontic, diplontic and haplodiplontic.

In bryophytes, the gametophyte represents the dominant phase. In pteridophytes, the sporophyte represents the dominant phase

All individuals have different ways of implementing their values and culture. Irrespective of these, all should be respected and allowed to live with dignity.

Q18. Write the components of the cell wall of Rhodophyceae and Phaeophyceae.

Solution

Group of algae Components of cell wall Rhodophyceae Cellulose, pectin and polysulphate esters Phaeophyceae Cellulose and algin  

Q19. Give any two examples of plants which exhibit a haplontic life cycle.

Solution

Chlamydomonas and Spirogyra

Q20. Write any two differences between Chlorophyceae and Rhodophyceae.  

Solution

Chlorophyceae     Rhodophyceae     1. Food is stored in the form of pyrenoids.     1. Food is stored in the form of floridean starch.     2. Chlorophyll a and b are present.     2. Red pigment called r-phycoerythrin is present.        

Q21. What does a pollen chamber in a gymnosperm represents?

Solution

In gymnosperms, the pollen chamber represents a cavity in the ovule in which pollen grains are stored after pollination.

Q22. What is the unique feature of bryophytes? 

Solution

The main plant body of bryophytes is gametophytic which is independent and may be thallose or foliose. The sporophyte is differentiated into foot, seta and capsule and is partially or fully dependent on the gametophyte.

Q23. Write the pigments found in members of the Phaeophyceae group of algae.

Solution

Chlorophyll a, chlorophyll c, carotenoids and xanthophyll (fucoxanthin).

Q24. Multicellular branched rhizoids and leafy gametophytes are characteristics of which group? 

Solution

In pteridophytes, the gametophyte generation is reduced and the sporophyte is well developed. In bryophytes, the gametophyte constitutes the well-developed generation, but it is foliose in mosses. 

Q25. Explain the modes of reproduction in Ulothrix.

Solution

In Ulothrix, reproduction may occur by the following methods: 1. Vegetative reproduction by fragmentation or by formation of different types of spores. 2. Asexual reproduction by flagellated zoospores. 3. Sexual reproduction by the isogamous, anisogamous or oogamous fusion of gametes.

Q26. Describe the plant body of brown algae.

Solution

The plant body of brown algae is attached to the substratum by a holdfast.   It has a stalk called stipe. The frond is a leaf-like photosynthetic organ of the plant body.

Q27. Distinguish between monocotyledons and dicotyledons.

Solution

Monocotyledons Dicotyledons 1. Seeds have single cotyledon. 1. Seeds have two cotyledons. 2. Leaves show parallel venation. 2. Leaves show reticulate venation.  

Q28. Which plant is commonly known as maiden hair fern?

Solution

Adiantum is commonly known as maiden hair fern. 

Q29. Why are bryophytes called amphibians of the plant kingdom?

Solution

Bryophytes can live in soil, but they are dependent on water for sexual reproduction; therefore, they are called amphibians of the plant kingdom.

Q30. What is protonema?

Solution

Protonema is the first stage in the gametophytic phase of a moss.

Q31. Describe the events which occur during the life cycle of an angiosperm.  

Solution

During pollination, the pollen grains germinate on the stigma.     This results in the formation of pollen tube which grows through the style and reaches the ovule.     When the pollen tube enters the sac, two male gametes are discharged.     One male gamete fuses with the egg cell and forms a zygote.     The second male gamete fuses with the diploid secondary nucleus and produces the triploid primary endosperm nucleus (PEN).     Because the fusion occurs twice, it is called double fertilisation.     The zygote develops into an embryo, while the primary endosperm nucleus develops into endosperm.     The endosperm provides nourishment to the developing embryo.     The synergids and antipodals of the egg apparatus degenerate after fertilisation.     At the end of this cycle, ovules develop into seeds which give rise to a new plant (sporophyte) while ovaries develop into fruits.  

Q32. Name the pigment present in the members of Rhodophyceae.

Solution

R-phycoerythrin

Q33. Name the diploid phase in the plant with a haplontic life cycle.  

Solution

The zygote is the diploid phase in a plant with a haplontic life cycle.  

Q34. Describe the structure of the vegetative cell of Chlorophyceae.  

Solution

The vegetative cell has a cell wall made of cellulose.     The cell wall is covered with a gelatinous coating of algin.     The protoplast of vegetative cells contains plastids, vacuole and nucleus.  

Q35. Write important characteristics of gymnosperms.

Solution

Characteristics of Gymnosperms:

Ovules are not covered by ovary.

Seeds are naked.

Gymnosperms exhibit a tap root system.

Gymnosperms are heterosporous.

(Write any 3)

Q36. Define flower.

Solution

A flower is a special reproductive structure in angiosperms in which the pollen grains and ovules develop.

Q37. Define pollination.

Solution

Pollination is the transfer of pollen grains, after their dispersal, from the anthers to the stigma of the pistil of the same flower or different flower of the same species.

Q38. Where are the sex organs produced in the plant body of moss?  

Solution

In moss, the sex organs are produced at the apex of leafy shoots.  

Q39. Draw diagrams of a) Volvox b) Chara  

Solution

a) Volvox:   b) Chara:

Q40. Distinguish between haplontic and diplontic life cycles.  

Solution

Haplontic Life Cycle     Diplontic Life Cycle    

Gametophytic phase is dominant.  

Sporophytic phase is dominant.  

Sporophyte is in the form of a diploid zygote.  

Gametophyte is single celled or few celled.  

   

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