Question # 1

Differentiate between parthenocarpy and apomixes.

Ans 1: Apomixes: In apomixes a diploid cell either from the nucellus or megaspore develops into a functional embryo in the absence of a male gamete.The rest of the ovule develops into seed and ovary into fruit.
Ans 2: Parthenocarpy: Formation of fruit without fertilization is called parthenocarpy. For example seedless grapes and banana.

Question # 2

Discuss diakinesis in meiosis.

Ans 1: During this phase the condensation of chromosomes reaches to its maximum.At the same time separation of homologous chromosomes is completed,but still they are united at one point,more oftenly at ends.Nucleoli disappear.

Question # 3

Give adaptation of marine fish for its survival in cold environment.

Ans 1: These fishes have a thick layer of insulting fat called blubber, which prevent excess heat loss from the body.

Question # 4

Explain the importance of gene sequencing.

Ans 1: i.Human pathogens can be sequenced
ii.Disputed parentage can be settled
iii.Suspected culprits can be identified

Question # 5

What are commercial applications of abscisic acid?

Ans 1: Abscisic acid can be sprayed on tree crops to regulate fruit drop at the end of the season.This removes the need for picking over a long time span.
Ans 2:

Question # 6

Differentiate between neurula and neurocoel.

Ans 1: Neurula: In the embryo of 24 hrs the neural folds are clearly visible,at this stage embryo is called neurula.
Ans 2: Neurocoel: In the chick development with the formation of neural tube,there is formation of central nervous system and the cavity enclosed is called neurocoel.

Question # 7

What is morula?

Ans 1: After fertilization of egg it divides repeatedly by mitotic division resulting in a ball of cells called morula

Question # 8

Define Succession.Name its types.

Ans 1: Succession is a sequence of changes in the community structure of an ecosystem over a period of time.In each case succession is initiated by a few hardy invaders called pioneers ant ends with a diverse and relatively stable climax community.e.g succession start on a bare rock in known as xerosere.
Ans 2: i) Primary succession ii) Secondary succession.

Question # 9

What are nucleotides?

Ans 1: Nucleotide is structural unit of DNA. It composed of nitrogenous base,pentose sugar and phosphate group.

Question # 10

Differentiate between convergent and divergent evolution.

Ans 1: Evolutionary processes that leads to the formation of homologous structures is called convergent evolution.
Ans 2: Evolutionary processes which leads to the formation of analogous structures in organisms is called divergent evolution.

Question # 11

Define biorhythms and gives its types.

Ans 1: In living organisms the behavioral activities occur at regular intervals which are called biorhythms.
1. Circannual rhythms (365 days)
2. Diurnal rhythms (24 hours)

Question # 12

Define leading and lagging strand of DNA.

Ans 1: Lagging strand is that strand of DNA which is discontinuously synthesized while the strand of DNA which is continuously synthesized is called leading strand.

Question # 13

What events occur in anaphase of mitosis?

Ans 1: During anaphase of mitosis spindle contract and centromere divides and two sets chromosomes are formed.Each set of chromosomes moves toward opposite poles.So that each pole receive one set of chromosomes.

Question # 14

Describe the animal life of grass land ecosystem.

Ans 1: Animals of deserts are mostly nocturnal (they hide during day and come out during night)they do so to avoid too much heat and water loss.Desert animals include horned lizards,snake and other reptiles.Mammals include kangaroo,rats,Birds include burrowing owl.

Question # 15

What is average rainfall in temperate deciduous forests?

Ans 1: The average rain fall in temperate deciduous forest is 750mm to 150mm/annum.

Question # 16

What is leutinnizing hormone(LH). Write its role

Ans 1: LH works with FSH to stimulate oestrogen secretion and rupture mature follicles to release ovum. It also causes leutinization of follicle after ovulation and along with prolactin maintains corpus leuteum.

Question # 17

Write symptoms of Turner's syndrome.

Ans 1: Individuals with this condition do not survive pregnancy and aborted.Those who survive have female appearance with short stature webbed neck,without ovaries and complete absence of germ cells.

Question # 18

What is importance of kinetochore in the allignment of chromosomes during mitosis?

Ans 1: Spindle fibers attaches at kinetochore of chromosomes and they help to align chromosomes at the center of cell to from equatorial plate or metaphase plate.

Question # 19

Explain the term homology with a suitable example.

Ans 1: Similarity in structure due to common ancestral origin is called homology. Homologous organs are best example of homology like flipper of whale,front leg of horse,arm of man,wing of bird.

Question # 20

Differentiate between food chain food web.

Ans 1: Food Chain: Process of eating and being eaten is called food chain.
Ans 2: Food web: Combination of different food chains is called food web.

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