Mention the importance of LH surde during menstrual cucle.

1

(a)

LH surge (maximum level of luteinizing hormone) leads to ovulation,i.e. the rupture of mature Graafian follicle and the consequent release of ovum.

What is the significance of ampullaryisthmic junction in the female reproductive tract?

1

(a)

Ampullary-isthmic junction is the site in the fallopian tube where fertilisation occurs.

What is the cross between the progeny of F₁ and the homozygous recessive parent called? How is it useful?

1

(a)

- It is called a test cross.

- It helps to determine the genotype of the F₁ individual with dominant phenotype.

Even if a character shows multiple allelism an individual will only have two allels for that character.  Why?

1

(a)

A diploid individual has only two sets of homologous chromosomes; hence only two alleles of a gene can be present on the homologous pair of chromosomes.

Why are proteins synthesised from spirulina called single cell proteins?

1

(a)

The protein produced by microbes, is called single cell protein.

Why is easier to culture meristems compared to permanenttissues?

1

(a)

Meristems have cells which have the capacity to divide,whereas in permanent capacity to divide, whereas in permanent tissues, the cells have lost the property of divition; some cells will have to undergo de-differentiation to produce new plants.

What is interaction between two species called?

1

(a)

Symbiosis.

What will happen to a well-growing herbaceous plant in the forests, it it is transplanted outside the forest in a park?

1

(a)

It may not grow well because of chage in its microlimate.

Name a recombinant vaccine that is currently being used in vaccination pro-grammes

1

(a)

Hepatitis-B vaccine.

What modification is done on the Ti-plasmid of Agrobacterium tumefaciens to convert it into a cloning vector?

1

(a)

Tumour inducing (Ti) plasmid of Agrobacterium tumefaciens is modified into a cloning vector by removing/ altering the gene responsible for its pathogenic property.

Give the names and functions of the hormones involved in the process of spermatogenesis.Write the names of the endocrine glands from where they are released.

1

(a)

Hormone	Endocrine  gland	Function
(i) FSH	Anterior pituitary	Stimulates Sertoli cells to secrete some factors which help in spermatogenesis.
(ii)ICSH/LH	-do-	Stimulates Leydig's cells of testes to secrete androgens (especially testosterone) which regulate spermatogenesis.

Reproductive health refers only to healthy reproductive functions.Comment.

1

(a)

Yes .Reproductive health is a state of physical, physiological, behavioural and social fitness for leading a responsible, safe and satisfying reproductive life.

The enzyme DNA polymerase on E.coli is a DNA-dependent polymerase and also has the ability to proof-read the DNA strand being synthesised. Explain. Discuss the dual polymerase.

1

(a)

(i) The DNA polymerase catalyses the addition of nucleotides, i.e. polymerization of nucleotides to form a DNA strand in the 5' -3' direction only
(ii) In prokaryotes, It removes any wrong base added to the DNA strand being synthesised.

Given below is the sequences of the coding strand of DNA in a transcription unit 3' AATGCAGCTATTAGG -5'. write the sequence of:
a) It's complementary strand
b)The mRNA.

1

(a)

a) 5'-TTACGTCGATAATCC-3'
B) 3'-AAUGCAGCUAUAGG-5'

What is diapause and its significance?

1

(a)

The suspended stage of development by an organism inorder to overcome the unfavourable environment conditions is called diapause.
Significance. Passing unfavourable conditions without any harm to the organism.

What would be the growth rate pattern, when the resources are unlimited?

1

(a)

In case of unlimited resources, the pattern of growth rate is exponential.

What is high altitude sickness ? Write its symptoms.

1

(a)

High altitude sickness is the disorder which a plain dweller surfaces when he/she goes to a high altitude area like Andes and Himalayas. It is characterized by nausea, fatigue, heart palpitation, etc.

What is nucellus?

1

(a)

It is the mass of parenchymatous tissue surrounded by integuments in an ovule. It encloses embryo sac and provides nourishment to the developing embryo

Why is distillation required for producing certain alcoholic drinks?

1

(a)

Distillation increases the alcohol content in alcoholic drinks.

Give the name of the type of synthesis A and B in the replication fork of DNA as shown below.

1

(a)

A-Continuous synthesis,
B-Discontinuous synthesis

Give a reason for the following:
i)The animals exhibiting external fertilization discharge large number of gametes.
ii)Marchantia is a dioecious plant.

1

(a)

i) The organism exhibiting external fertilization discharge a large number of gametes into the water to increase the chances of fertilization.
ii)In Marchantia, male and female reproductive organs are present in separate individuals.Such type of plants is called dioecious plants.

How is stratification represented in forest ecosystem?

1

(a)

Stratification is the way in which different species in an ecosystem are placed or arranged vertically, occupying different levels.It is a way of minimising competition for limited resources vital for survival.

List any two ways of measuring the standing crop of a trophic level.

1

(a)

Two ways of measuring the standing crop of a trophic level are:
(i) Biomass of living organisms
(ii) The number in a unit area.

Rearrange the various reproductive events in the correct order in which they occur in a flowering plant. Embryogenesis, gametogenesis, pollination, fertilisation.

1

(a)

The correct order of the reproductive events is Gametogenesis, pollination, fertilisation, embryogenesis.

What is the role of enzymes like chitinase and lysozyme in genetic engineering?

1

(a)

Protease is added because it helps in digesting proteins and helps in the breakdown of cell wall by dissolving it.