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Model Activity Task 1 Life Science Solution

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1) Draw a neat diagram of neurone and label the following parts:
(a) Dendron (b) Schwann cell (c) End brush (d) Axolemma

2) Mention the role of meiosis in producing variation in organisms.Write three characteristics
of anaphase stage of mitosis.
Ans: During meiosis, there may be crossing over between nonsister chromatids which results into “shuffling and reshuffling” of parental and maternal genes. Thus new genotypic variation may occur in the organism.
i. Centromeres od chromosome divide separating thw two chromatids of each chromosome.
ii. Chromosomes are single stranded chromarids.
iii. These chromatids, tge so called daughter chromosomes move to opposite poles by contaction of spindle fibres.

3) Write three roles of the plant hormone which helps in controlling apical dominance.
Mention the role of insulin hormone in controlling the level of carbohydrate in blood.
Ans: i)Apical dominance occurs when the shoot apex inhibits the growth of lateral buds so that the plant may grow vertically.
ii)The apical bud produces a hormone, auxin, (IAA) that inhibits growth of the lateral buds further down on the stem towards the axillary bud.

Insulin is the key hormone of carbohydrate metabolism, it also influences the metabolism of fat and proteins. It lowers blood glucose by increasing glucose transport in muscle and adipose tissue and stimulates the synthesis of glycogen, fat, and protein.

4) Determine the importance of fins of fish in swimming. Which types of bone joint can be
seen in knee and shoulder?
Ans: Fins are the appendages on the body of fishes. There are altogether seven fins present in each fish. Two are paired and three are unpaired fins. Fins helps to maintain stability and direction of movements of the fish.
i. Pectoral and pelvic fins help animals in keeping the body in horizontal position.
ii. Dorsal fins facilitates anterior movement.
iii. The tail fins act as a steering apparatus for change of direction.
iv. The anal fin maintains the vertical position of fish.
Hinge joint is seen in knee and ball and socket joint is seen in shoulder.

5) Draw the morphology of eukaryotic chromosome and label the following parts:
(a) Chromatid (b) Centromere (c) Nucleolar organizer (d) Telomere

6) What are the reasons behind animal locomotion? ‘The mode of action of flexor and extensor
muscle is antagonistic in nature’ – explain with the help of suitable example.
Ans: Reasons behind are:-
i. To acquire food :- Animals are not able to prepare their own food matters, hence in search of food they have to move from one place to another.
ii. Shelter :- In order to live a normal life and to perform all living functions properly, a suitable shelter is necessary for all animals.
iii. Avoiding capture by predators :- Animals have to go under locomotion in order to protect themselves from danger.
Movement of flexor muscle occurs around the frontal transverse axis and during movement the angle between the bones becomes more acute. E.g. Bicep of hand while in extensor muscle tge movement takes place just in opposite direction to flexion. E.g. Triceps of hands.

7) ‘The S phase of cell cycle is termed as synthesis phase’ – judge the accuracy of this statement.
Mention the differences between DNA and RNA.
Ans: The S phase of a cell cycle is termed as synthesis phase because in this phase new DNA is synthesized on the mother DNA template. So, the amount of DNA is doubled. Histone protein is also synthesized in S phase. Each chromosome now consists of two chromatids joined at the centromere.
i. Pentose sugar is deoxyribose sugar.
ii. Nitrogen base is thymine.
i. Pentose sugar is ribose sugar.
ii. Nitrogen base is uracil.

8) ‘Adrenaline hormone plays an important role in combatting emergency situations’ – explain.
Write the differences between tropic and nastic movement.
Ans: Some hormones are secreted in the body during emergent condition like fear, anger, depression etc. These hormones are adrenalin from adrenal medulla and cortisol from adrenal cortex. Adrenalin is known as emergency hormone or stress hormone, which causes widespread reponses such as increase of heart rate, blood pressure and so on, by which a subject is able to fight out situation successfully.
Tropic Movement :-
i. It is induced growth movement of curvature.
ii. Auxin plays most significant role in tropic movement.
Nastic Movement :-
i. It is induced movement of curvature.
ii. Auxin plays no direct role in nastic movement.

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