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ANSWER KEY
1. Genetic drift
2. Spermiogenesis
3. Human
Genome Project.
4. (b) 14th day
5. Edward
Wilson
6. Propionibacterium
sharmani
7. (a)
Turner’s syndrome. Genetic constitution: 44A + X0
(b)
Sterile, Ovaries are rudimentary. Lack of secondary sexual characters. Dwarf. Mentally
retarded (Any 2).
8. (a)
Yes. Methanogens are the microbes that can be used for biogas production.
(b)
Rhizobium, Azotobacter, Cyanobacterium, Mycorrhiza etc.
(any 2)
9.
|
A |
B |
|
Ring worms |
Trichophyton |
|
Cytokine barriers |
Interferon |
|
Oncogenes |
Cancer |
|
HIV |
Helper T-cells |
10. (a)
An antibody. It is produced by B-lymphocytes (B-cells).
(b) These are the proteins to
fight the pathogens. i.e., gives immunity.
11. (a)
It states that life came out of decaying and rotting matter like straw, mud
etc.
(b) Louis Pasteur disproved this theory.
12. (a)
Implantation
(b) Lactation
(c) Acrosome
(d) Corpus luteum
13. (a)
Test cross. It is the cross between F1 hybrid with a recessive parent.
(b)
It is used to find out the unknown genotype of a character.
14. (a)
Warning signs:
· Drop in academic performance and absence from
school.
· Lack of interest in personal hygiene.
· Withdrawal and isolation.
· Depression, fatigue, aggressive and rebellious
behaviour.
· Change in sleeping and
eating habits.
(b)
Prevention and control:
· Avoid
undue peer pressure.
· Education
and counselling.
· Seeking
help from parents and peers.
· Looking
for danger signs.
·
Seeking professional and
medical help.
15. (a)
T.H Morgan
(b) • They can grow on
simple synthetic medium.
• Short generation time.
• Breeding can be done throughout the year.
•
Hundreds of progenies per mating.
(c) Tightly linked genes show low
recombination. Loosely linked genes show high recombination.
16. (a)
Extinction of the parasites when the host is extinct.
In
co-evolved plant-pollinator mutualism, extinction of one causes the extinction
of the other.
(b)
Biodiversity (species richness) is highest in tropics because
· Tropics
had more evolutionary time.
· Relatively
constant environment (less seasonal).
· They
receive more solar energy which contributes to greater productivity.
(c)
Hotspots are the regions with very high species richness, high degree of
endemism but most threatened.
17. Divergent
evolution: It is the evolution by which related species become
less similar to survive and adapt in different environmental condition.
Convergent
evolution: It is the evolution by which unrelated species
become more similar to survive and adapt in similar environmental condition.
18. a.
(i) Digestion of DNA by restriction endonucleases. (ii) Hybridization by
radioactive VNTR probe.
b.
DNA carries non-coding repeated sequences called variable number tandem repeats
(VNTR). VNTR is specific in each person.
c.
Yes. It is a forensic tool to solve paternity, rape, murder etc.
19. (a)
Central Dogma of Molecular Biology:
(b) Salient features of genetic code:
• Triplet code. 61 codons code for amino acids. UAA, UAG & UGA are stop codons (Termination codons).
• Genetic code is universal.
•
No punctuation b/w adjacent
codons.
•
An amino acid is coded by many
codons. So the code is degenerate.
(c) AUG is the initiator codon. Methionine is the
amino acid coded by it.
20. (a)
Vasectomy
(b)
Tubectomy
(c) Easily available, reversible, prevent STDs, gives privacy to the user.
(d) (i) Gamete Intrafallopian Transfer (ii) Intracytoplasmic Sperm Injection.