Short Answer Type(a) Name any two places where it is essential to install electrostatic percipitators. Why is it required to do so?
(b) Mention one limitation of the electrostatic precipitator.
Prior to a sports event blood and urine samples of sports-persons are collected for drug tests.
(a) Why is there a need to conduct such tests/
(b) Name the drugs the authorities usually look for.
(c) Write the generic names of two plants from which these drugs are obtained.
Given below is a list of six micro-organism. State their usefulness to humans.
(a) Nucleopolyhedrovirus
(b) Saccharomyces cervisiae
(c) Monascus purpureus
(d) Trichoderma polysporum
(e) Peniciliu notatum.
(f) Propionibacterium sharmanni
Reproductive and Child Healthcare (RCH) programmes are currently in operation. One of the major tasks of these programmes is to create awareness amongst people about the wide range of reproduction related aspects. As this is important and essential for building a reproductively healthy society.
(a) Providing sex education in schools in one of the ways to meet this goal. Give four points in support of your opinion regarding this statement.
(b) List any two 'indicators' that indicate a reproductively healthy society.
Describe the experiment that helped demonstrate the semi-conservative mode of DNA replication
Long Answer Type(a) Explain the post-pollination events leading to seed production in angiosperms.
(b) List the different types of pollination depending upon the source of pollen grains.
(a) Briefly explain the events of fertilisation and implantation in an adult human female.
(b) Comment on the role of placenta as an endocrine gland.
(a) During coitus, the semen having sperms is released into the vagina.
i. It passes through the cervix of the uterus and reaches the ampullary-isthmic junction of the fallopian tube.
ii. The ovum is also released into the junction for fertilisation to occur.
iii. The process of fusion of the sperm and the ovum is known as fertilisation.
iv. During fertilisation, the sperm induces changes in the zona pellucida and blocks the entry of other sperms. This ensures that only one sperm fertilises an ovum.
v. The enzymatic secretions of the acrosomes help the sperm enter the cytoplasm of the ovum.
vi. This causes the completion of meiotic division of the secondary oocyte, resulting in the formation of a haploid ovum (ootid) and a secondary polar body.
vi. Then, the haploid sperm nucleus fuses with the haploid nucleus of the ovum to form a diploid zygote.
vii. Mitosis starts as the zygote moves through the isthmus of the oviduct (cleavage) and forms 2, 4, 8 and 16 daughter cells called blastomeres.
viii. The 8−16 cell embryo is called a morula, which continues to divide to form the blastocyst. The morula moves further into the uterus.
ix. The cells in the blastocyst are arranged into an outer trophoblast and an inner cell mass.
x. The trophoblast gets attached to the uterine endometrium and the process is called implantation. This leads to pregnancy.
xi. The inner cell mass gets differentiated to form the embryo.
(b) Placenta acts as an endocrine gland and produces the following hormones
i. Human chorionic gonadotropins (hCG),
ii. human placental lactogen (hPL),
iii. Estrogen and progesterone
iv. Relaxin (in the later stages of pregnancy).
These hormones support foetal growth and help in the maintenance of pregnancy. Hormones like oestrogen, progestogen, cortisol, thyroxine and prolactin are increased several folds in the maternal blood.
(a) How are the following formed and involved in DNA packaging in a nucleus of a cell?
(b) Differentiate between Euchromatin and Heterochromatin
(a) Why should we conserve biodiversity? How can we do it?
(b) Explain the importance of biodiversity hot-spots and sacred groves.
(a) Represent diagrammatically three kinds of age-pyramids for the human population.
(b) How does an age pyramid for human population at given point of time helps the policy makers in planning for the future.
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