(i)Why does DNA replication occur in small replication forks and not in its entire length?
(ii)Why is DNA replication countinuous and discountinuous in a replication fork?
(iii)Explain the importance of 'origin of replication' in a replication fork.

3

(a)

Anthropogenic action can hasten evolution. Explain with the help of a suitable example.

3

(a)

The study of
(i) fossils of dinosaurs
(ii) forelimbs of Cheeta, bat and human
(ii) thorns of Bougainvillea and tendril of Cucurbita shows that evolution of life forms has indeed taken place on earth. Explain.

3

(a)

An organic farmer releies on natural predection for controlling plant pests and diseases. Justify giving reasons why this is considered to be holistic approch.

3

(a)

If implementation of better techniques and new strategies are required to provide more efficient care and assistance to people, then why is there a statutory ban on amniocentesis? Write the use of this technique and give reason to justify the ban.

3

(a)

Women experience two major events in their lifetime one at menarche and the second at menopause, mention the characteristics of both the events.

3

(a)

Why are green algae not likely to be found in the deepest strata of the ocean?

3

(a)

(a) Name the type of synthesis 
(b) Occurrence in the types of synthesis and as shown below: 

3

(a)

(i) The graph given alongside represent the growth patterns of two types of aquatic organisms over a brief period of times in a water body surrounded by an agricultural land extensively supplied with fertilisers.Identify the organisms that would represent (i) A and (ii) B.
(ii) State the reason for such a change in the water body and also write the term given to it.

3

(a)

(a) List two invasive techniques being used to determine the genetic disorders of the foetus.
(b) Can you name any non-invasive technique being used by physician now a days to determine the foetal condition?

3

(a)

(a) At present, Reproductive and Child Health Care(RCH) Programmes are launched by the government of India. Name the two major aims and objectives of these programmes.
(b) Name the prominent Assisted Reproduction Technologies being used today to assist infertile couples to have children.

3

(a)

(a) Some men have abnormally low sperm count in seminal fluid. Also, some women cannot normally conceive because of any of the following reasons:
(i) They cannot produce ova,
(ii) They have blocked oviducts, or
(iii) They have spermicidal secretions in the vagina.
In such couples, one technique is commonly used. Name that Assisted Reproduction Technique.
(b) At what stage, fertilized egg is transferred into the fallopian tube or uterus of the mother in this technique?

3

(a)

Few gaps have been left in the following table. Fill up the gaps.

Restriction Enzyme	Source	Recognition sequence and site of cleavage
Bam HI	Bacillus amyloliquiefaciens H	a
Eco RI	b	​​​​\(\downarrow \) 5'-G-A-A-T-T-C-3' 3'-C-T-T-A-A-G-5'                       \(\uparrow \)
c	Haemophillus influenzae Rd	\(\downarrow \)        5'-G-T-C-G-A-C-3' 3'-C-A-G-C-T-G-5'                \(\uparrow \)

3

(a)

What will happen if -
(i) A plasmid vector is digested with Eco RI at a single site
(ii) A sample of human DNA is digested with Eco RI.
(iii) The two samples (plasmid and human DNA) are allowed to hybridise in presence of DNA ligase.

3

(a)

Name 'A' and 'B' in the following equations:
Sugary juice \(\underrightarrow { 'A' } \) Ethanol + H₂ O ; Ethanol \(\underrightarrow { Acetobacter\quad aceti } \) B

3

(a)

What is the main reason for low milk production in  India? How can it be improved?

3

(a)

Here some correct and some wrong statements.Correct only those statements which are wrong:
(a) The genetic code is universal 
(b)The genetic code is ambiguous
(c)The genetic code is regenerated.
(d)Transfer RNA(tRNA)carry amino acids to mRNA codons and used again and again in transcription.
(e)UAA, UAG and UGC are terminator codon
(f)Lac operon consists of regulatory genes, operator gene,structural and promoter gene

3

(a)

What do you understand by 5'-end and 3'-end?

3

(a)

Identify the type of inheritance shown in the following pedigree diagram.

Observe the following figure and answer the following questions-
(a) Name the plant in which the above cross was made and by whome?
(b) What phenomenon does this cross shows.

3

(a)

When is the structure and composition of a community expected to remain unchanged?

3

(a)

Can the host-parasite relationship provide evidence for evolution? Explain.

3

(a)

(a) Study the graph carefully and correlate the follicular growth that takes place according to hormonal levels on 
(i)  1-5 days
(ii) 12-14 days
(iii) 25-28 days (if the ovum is not fertilized).
(b) Specify source(s) of the hormones mentioned n the graph.

3

(a)

What kind of evolution has brought similarity in the following:
(i) Placental cat and a marsupial cat
(ii) Fishes and whales
(iii) Darwin's finches

3

(a)

Why are cloudy, dusty and humid nights warmer than the clear, dust-free and dry nights?

3

(a)

You might have been seen in TV or read in newspaper about bird flu. This has created a fear in the country and had drastically affected egg and chicken consumption.
Find out more about this and discuss whether the panic reaction was justified.

3

(a)