(a) What is the fate of part labelled as 'A'?
(b) How does chromosome number change when 'A' changes
to 'B'?- Karyotype of a human male showed the presence of an
additional X chromosome. What is the condition called and
what are the symptoms of such abnormality? - Refer to the given figure and answer the following
questions.
(a) What does the figure represent?
(b) Describe different types of such molecules.- (a) Genetic code is degenerate. How?
(b) hnRNA is the precursor of mRNA. Justify.
- Give diagrammatic representation of regulation of gene
expression in lac operon of E. coli. - Alien species cause loss of biodiversity. Justify your answer
with two examples.
OR
(a) What are the main objectives behind biofortification?
(b) Name one variety each of wheat, Brassica and cauliflower
that are resistant to diseases and name the diseases to
which they are resistant.
- Pyramid of numbers in case of forest ecosystem shows
deflection from its regular shape. Discuss. - Refer to the given flow chart and answer the accompanying
questions.
(a) Name the hormones A, B and C.
(b) How does hormone inhibin regulate male reproductive
system?(c) Mention the role of sertoli cells in male reproductive system.- With the help of diagrammatic representation only, explain
pre-pollination development of a male gametophyte in
angiosperms.ECTION
SECTION - D - Anuradha visited her grandparents who live in a village.
On a visit to an agricultural field, she observed that
farmers were using pesticides. She immediately asked her
grandfather to organise a meeting with local farmers. In
the meeting, she explained and discussed other alternate
methods that farmers can use to control weeds and pests
without harming the environment.
(a) What values are reflected here by Anuradha?
(b) Why did Anuradha ask her grandfather to organise the
meeting?
(c) Which alternate methods is Anuradha talking about?
(d) Explain biopesticides with examples.
SECTION - E - With the help of suitable diagrams, describe the
developmental stages of an embryo sac of angiosperms
from a megaspore mother cell.
OR
Long molecules of DNA in eukaryotes are packed, so as to
make it adjust in a tiny nucleus. How? - (a) In nature, populations of different species occur
together. List any two interactions which they exhibit within
a community?
(b) What type of behavioural response do desert lizards show
in response to variations in the environment?
OR
What is DNA fingerprinting and what is its procedure? - Give diagrammatic representation of various steps of rDNA
technology.
OR
(a) Placenta acts as an intimate connection between the mother
and the foetus as well as an endocrine tissue. Discuss.
(b) Why are IUDs considered as ideal contraceptives for
women?
SOLUTIONS - Entry of sperm into ovum at the time of fertilisation
stimulates the secondary oocyte to complete the suspended
second meiotic division. - Ethidium bromide is used to stain DNA fragments followed
by exposure to UV radiations. This gives bright orange
colour to DNA fragments and helps in their separation. - Patients of cancer are given substances called biological
response modifiers such as a-interferons which activate
their immune system and help in destroying the tumour.