Question 1

Read the following statements and select the correct ones.(i) Conidia are the asexual propagules restricted to Kingdom Fungi.(ii) A piece of potato tuber having at least one eye (or node) is capable of giving rise to a new plant.(iii) Ginger propagates vegetatively with the help of its underground roots.(iv) Fleshy buds which take part in vegetative propagation are called bulbils, present in Dioscorea, Agave, etc.

Accepted Answer

Ginger propagates vegetatively with the help of rhizome. Rhizomes are main underground stems which store food for perennation during unfavourable conditions. These have buds for formation of new aerial shoots during favourable conditions.

Question 2

Which of the following feature(s) is/are common to both wind and water-pollinated flowers?I.	Pollen grains are long and ribbon-like.II.	Stigma is large and feathery.III.	The flowers are not colourful.IV.	The flowers do not produce nectar.

Accepted Answer

In given features, only I and II features are common to both wind and water-pollinated flowers.Stigma is large and feathery in wind-pollinated flowers. Pollen grains are long and ribbon-like so that, it can float below the surface of the water in water-pollinated flowers.Thus, option (c) is correct.

Question 3

Find out the correct sequence of events taking place in pollen-pistil interaction.I.	Pollen tube enters one of the synergids and bursts to release male gametes.II.	Pollen tube enters ovule through micropyle of ovary.III.	Pollen tube grows through the stigmatic tissue and then style.IV.	Pistil recognises the compatible pollen and accepts it.Choose the correct option.

Accepted Answer

Pollen-pistil interaction includes:Recognition of compatible pollen- The pistil has the ability to recognise the right compatible pollen of the same species and to reject the pollen grains that are incompatible either of same species or of other species.Growth of a pollen tube-The contents of the pollen then move into this tube.Entry of pollen tube into the ovule- After reaching the ovary, the pollen tube enters the ovule through one of synergids at micropylar end and release male gametes.Thus, the correct sequence of events taking place in pollen-pistil interaction is IV, III, II, I.

Question 4

Self-incompatibility is a process toI.	ensure cross-pollinationII.	prevent self-fertilisationIII.	ensure self-fertilisationIV.	genetic control for self-fertilisationChoose the correct process for given statements.

Accepted Answer

I, II and IV processes are correct for given statement.Self-incompatibility is a genetic mechanism, i.e. genetic control for self-fertilisation by preventing self-pollination, i.e. from the same flower or other flower of the same plant from fertilising the ovules by inhibiting pollen germination or pollen tube growth in the pistil. It ensures cross-pollination.Thus, option (d) is correct.

Question 5

Assertion (A): In the testis, spermatogenesis occurs in the seminiferous tubules and testosterone secretion takes place from the Sertoli cells.Reason (R): Testosterone brings growth and maturation of secondary sex organs and also the development of accessory sex characters.

Accepted Answer

A is false, but R is true. A can be corrected as-In the testis, spermatogenesis occurs in the seminiferous tubules and testosterone secretion takes place in interstitial cells.

Question 6

Assertion (A): Ovum retains most of the contents of the primary oocyte and is much larger than a spermatozoa.Reason (R): Ovum needs energy to go about in search of a spermatozoa for fertilisation.

Accepted Answer

A is true, but R is false and it can be corrected as-It is the sperm, which needs energy to move about in female reproductive tract in search of ova, so that fertilisation can take place.

Question 7

Which of the following events is related to the ovulation phase in human female?I.  Decrease in oestradiolII. Full development of Graafian follicleIII. Release of secondary oocyteIV. LH surge

Accepted Answer

Decrease in oestradiol is not associated with ovulation in human females. Oestradiol is also known as oestrogen which is a primary female sex hormone. During the ovulation in human females, level of oestradiol increases. Its main function is to mature and maintain the reproductive tract.

Question 8

Assertion (A): Production of FSH and LH increases in the ovulation phase.Reason (R): Due to decrease in the level of LH, ovulation (releasing of ova) takes place.

Accepted Answer

A is true, but R is false. R can be corrected asIn menstrual cycle, rapid secretion of LH leads to its maximum level during mid-cycle. It is called LH surge. It induces rupture of Graafian follicle, thereby releasing ovum (ovulation).

Question 9

The following statements are drawn as conclusions from the above data.I.  High level of hCG stimulates the synthesis of oestrogen and progesterone.II. High level of hCG stimulates the thickening of endometrium.III.The level of oestrogen and progesterone becomes high during pregnancy.Choose from above the correct conclusions.

Accepted Answer

Statements I and III are correct.Statements II is incorrect as high levels of oestrogen stimulates the thickening of the endometrium.

Question 10

State the role of the epididymis in male fertility.

Accepted Answer

The epididymis is the male sex accessory duct. The main function of the epididymis is to store the sperms for maturation and transport it to vas deferens. It is a coiled tube attached to both the testes through vasa efferentia. It connects the testes to vas deferens.When sperms reach the head of the epididymis, they are not mature and are not motile. Sperms take 2-6 days to mature in humans during their transit in the epididymis and become motile. Their motility is reduced in the epididymis until ejaculation. They are stored in the tail region and at the time of ejaculation, they are transported to the ejaculatory duct via vas deferens and finally come out of the urethra. The final maturation or capacitation of sperms only takes place in the female reproductive tract.

Question 11

Duration of division time in E.coli is:

Accepted Answer

The bacterium Escherichia coli can divide every 20 min in the laboratory under aerobic, nutrient-rich conditions. When cells divide rapidly, a new cycle of replication begins before the current cycle of replication is complete. At any given time, there can be six or eight replication forks synthesizing DNA simultaneously inside the cell.In order for the cell to divide every 20 minutes, it suffices for one replication cycle to complete every 20 minutes. This means that the origins are triggered every 20 minutes. When the daughter chromosome separates into daughter cells, they are already partially replicated in preparation for the next cell division.

Question 12

Which one of the following events is correctly matched with the time period in a normal menstrual cycle?

Accepted Answer

The reproductive cycle in the female primates (e.g. monkeys, apes and human beings) is called menstrual cycle.In human females, menstruation is repeated at an average interval of about 28/29 days, and the cycle of events starting from one menstruation till the next one is called the menstrual cycle.The cycle starts with the menstrual phase, when menstrual flow occurs and it lasts for 3-5 days. The menstrual flow results due to breakdown of endometrial lining of the uterus and its blood vessels which forms liquid that comes out through vagina. Menstruation only occurs if the released ovum is not fertilised. Lack of menstruation may be indicative of pregnancy. However, it may also be caused due to some other underlying causes like stress, poor health etc. The menstrual phase is followed by the follicular phase. During this phase, the primary follicles in the ovary grow to become a fully mature Graafian follicle and simultaneously the endometrium of uterus regenerates through proliferation. These changes in the ovary and the uterus are induced by changes in the levels of pituitary and ovarian hormones. The secretion of gonadotropins (LH and FSH) increases gradually during the follicular phase, and stimulates follicular development as well as secretion of estrogens by the growing follicles. Both LH and FSH attain a peak level in the middle of cycle (about 14th day). Rapid secretion of LH leading to its maximum level during the mid-cycle called LH surge induces rupture of Graafian follicle and thereby the release of ovum (ovulation).The ovulation (ovulatory phase) is followed by the luteal phase during which the remaining parts of the Graafian follicle transform as the corpus luteum. The corpus luteum secretes large amounts of progesterone which is essential for maintenance of the endometrium. Such an endometrium is necessary for implantation of the fertilised ovum and other events of pregnancy. During pregnancy all events of the menstrual cycle stop and there is no menstruation. In the absence of fertilisation, the corpus luteum degenerates. This causes disintegration of the endometrium leading to menstruation, marking a new cycle. In human beings, menstrual cycles ceases around 50 years of age; that is termed as menopause.

Question 13

If the haploid number in a flowering plant is 14. What shall be the number of chromosomes in integuments, antipodal cells, embryo, endosperm and nucellus respectively?

Accepted Answer

In order to calculate the number of chromosomes in the given parts of flower we must keep in mind their ploidy level.As the haploid number is 14, i.e., n=14, thereforeIntegument is a diploid cell 2n, so 2 x 14 = 28Antipodal cells are haploid so, n = 14Embryo is diploid, 2n = 2 x 14 = 28Endosperm is triploid, 3n = 3 x 14 = 42Nucellus is diploid, 2n = 2 x 14 = 28

Question 14

Rhizopus and Saccharomycescerevisiae yield respectively:

Accepted Answer

Rhizopus  yields lipase and Saccharomycescerevisiae  yields invertase enzyme.

Question 15

dB is a standard abbreviation used for the quantitative expression of

Accepted Answer

Unwanted sound is called noise and it is measured in terms of decibels (dB). Generally sound above 80 dB is called noise because it is considered as unpleasant to our ears.

Question 16

Which one of the following is the correct matching of the events occurring during menstrual cycle.

Accepted Answer

In secretory phase during ovulation, the follicle breaks and collapes under the continuous influence of Luteinising Hormone (LH). It begins to enlarge and forms a yellowish structure, called the corpus luteum. The corpus luteum plays an important role in the preparation of the endometrium for the implantation of the fertilised egg by secreting oestrogens and progesterone.

Question 17

Age of fossils in the past was generally determined by radio-carbon method and other methods involving radioactive elements found in the rocks. More precise methods, which were used recently and led to the revision of the evolutionary periods for different groups of organisms, include:

Accepted Answer

Electron Spin Resonance (ESR) measures number of charges occupying deep traps in crystal band gap. The basic principle of ESR is same as those for luminescence, i.e. electrons become trapped and stored as a result of ionising radiations e.g. dating of tooth enamel.

Question 18

Match the disease in column I with the appropriate items (pathogen/prevention/ treatment) in column II.

Accepted Answer

The correct match is A (ii), B (iii), C (iv), D (i)

Question 19

Read the following four statements (A-D) about certain mistakes in two of them.(A) The first transgenic buffalo, Rosie produced milk which was human alphalactalbumin enriched.(B) Restriction enzymes are used in isolation of DNA from other macromolecules.(C) Downstream processing is one of the steps of rDNA technology.(D) Disarmed pathogen vectors are also used in transfer of rDNA into the host.Which of the two statements have mistakes?

Accepted Answer

In 1997, the first transgenic cow, Rosie, produced human protein enriched milk. The milk contained the human alpha-lactalbumin and was nutritionally a more balanced product for human babies than natural cow-milk. Isolation of DNA from other macromolecule is achieved by treating the bacterial cells/plant or animal tissue with enzymes such as lysozyme (bacteria), cellulase (plant cells), chitinase (fungus).

Question 20

Select the incorrect statement:

Accepted Answer

Organic matter is produced by both autotrophs and heterotrophs. In former case, it is called gears primary productivity while in latter case, it is called secondary productivity.

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