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Question 14 Marks

Various parts of the plant such as stems leaves, and even fruits are modified into underground parts to perform various functions such as stems, leaves, and even fruits.
The stems in ginger and banana are underground and swollen due to storage of food. They are called rhizome. Rhizome of ginger is a modification of stem because it bears nodes, internodes, terminal buds, scaly leaves and buds, which give rise to aerial shoots. It is not a root because root does not have nodes and internodes. Also, rhizome does not perform the function of roots i.e. anchorage and absorption, rather it serve as reservoir for storage of food. Similarly, corm is an underground stem in Colocasia (jimikand) The tips of the underground stem in potato become swollen due to accumulation of food and forms tuber.

i. Observe the given flow chart and mention what are the four types of Underground stem modification also mention one example of each. (1)
ii. Ginger is an underground stem but why it is distinguished from a root? (1)
iii. Why do the tips of modified stems in potatoes become swollen? (2)

OR

Are all underground parts of a plant roots? (2)

Answer

i. • Rhizome - Ginger, turmeric.Banana
• Bulb - Tulips, Lilies, Daffodils, Onion, Garlic
• Corm Colocasia, Yam, Saffron
• Tuber - Potato, Artichokes
ii. It has nodes and internodes. Such nodes and internodes are not found in the roots.
iii. Modified stem in the potato is underground and it becomes swollen because food gets accumulated to form tubers.

OR

No. Many different parts of plants, like the stem, leaves and fruits, get modified to act as underground structures that can perform functions other than those of roots.

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Question 24 Marks

Sarcodines are unicellular/jelly-like protozoa found in fresh or sea water and in moist soil. Their body lacks a periplast. Therefore, they may be naked or covered by a calcareous shell. They usually lack flagella and have temporary protoplasmic outgrowths called pseudopodia. These pseudopodia or false feet help in movement and capturing prey. They include free-living forms such as Amoeba or parasitic forms such as Entamoeba. Zoo flagellates ciliates and I sporozoans are other groups of protozoan protists. They are all unicellular and heterotrophic. They may be holozoic, saprobic or parasitic.

i. Write two lines about flagellated protozoans and also mention some flagellated protozoans. (1)
ii. Observe the given protozoan classification and mention what is the basis of protozoan classification. (1)
iii. Mention some locomotory organs of protozoa. (2)

OR

Which protozoan group has two nuclei, macronucleus, and micronucleus? Mention characteristics of it. (2)

Answer

i. Flagellated protozoans are either free-living or parasitic protozoans that have flagella. Sleeping sickness is caused by parasitic versions of the parasite. Trypanosoma is a good example.
ii. • Locomotion
• Protozoan are eukaryotic having different shapes and sizes. Some are ciliated flagellated or both may be absent.
iii. a. Cilia
b. Flagella
c. Pseudopodia

OR

Ciliata has two nuclei, macronucleus, and micronucleus.
Ciliates are characterized as organisms propelled by rows of cilia and possessing two types of nuclei. They are a large macronucleus involved in vegetative functions of the organism, and a small micronucleus involved in sexuality.

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BIOLOGY Case study (4 Marks)

Case study (4 Marks)

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