Biotechnology: Principles and Processes — BIOLOGY STD 12 Science — Question

Read the following and answer any four questions from (i) to (v) given below:

The mature ovum or a female gamete is spherical in shape. The human ovum is almost free of yolk and is said to be alecithal. Human ovum loses its ability to be fertilised about 24 hours after ovulation. Refer to the given structure of ovum and answer the following questions.

1. Thick cellular layer formed of radially elongated follicular cells is:

1. Zona pellucida.
2. Plasma membrane.
3. Perivitelline membrane.
4. Corona radiata.

2. In humans, at which stage does ovum get released from ovary?

1. Secondary oocyte.
2. Oogonium.
3. Primary oocyte.
4. First polar body.

3. Cytoplasm of an ovum is enveloped by _____.

1. Zona pellucida.
2. Corona radiata.
3. Cell membrane.
4. Perivitelline space.

4. Select the correct option:

S. No	V	W	X
(a)	Cytoplasm	Zona pellucida	Plasma membrane
(b)	Cortical granules	Corona radiata	Zona pellucida
(c)	Cortical granules	Plasma membrane	Corona radiata
(d)	Cytoplasm	Corona radiata	Zona pellucida

5. Which of the following is not a characteristic of an ovum?

1. Nucleus of an ovum has prominent nucleolus.
2. Only one ovum formed from one oogonium.
3. It lacks centrioles.
4. It has very small amount of ooplasm.

Read the following and answer any four questions from (i) to (v) given below:
In testis, the immature male germ cells produce sperms by spermatogenesis that begins at puberty. It occurs in the seminiferous tubules of the testes. Seminiferous tubules are lined by germinal epithelium. Study the schematic representation of spermatogenesis and answer the following questions.

1. Which cell division occurs during multiplication phase?

1. Mitosis.
2. Meiosis I.
3. Meiosis II.
4. Both (b) and (c).

2. How many chromosomes are present in secondary spermatocyte and spermatid, respectively?

1. 46, 23
2. 46, 46
3. 23, 23
4. 23, XY

3. Transformation of L into M is known as:

1. Spermiation.
2. Spermateliosis.
3. Spermatogenesis.
4. None of these.

4. Select the correct option.

1. Type A spermatogonia grows to larger primary spermatocyte.
2. One spermatogonium forms two spermatids.
3. Spenniation is the release of sperms from seminiferous tubules.
4. Primary spermatocyte undergoes mitosis to form secondary spermatocytes.

5. Which hormone acts on spermatogonia to stimulate sperm production?

1. LH.
2. GnRH.
3. ABP.
4. FSH.

Differentiate between Monohybrid & Dihybrid Cross.

Read the following text carefully and answer the questions that follow:
The reproductive cycle in female primates (e.g. monkeys, apes and human beings) is called the 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 Anita has show Diagrammatic presentation of various events during a menstrual cycle.

i. What role do pituitary gonadotropins play during the follicular and ovulatory phases of the menstrual cycle? (1)
ii. The first half of the menstrual cycle is called the proliferative phase as well as the follicular phase. Give reason.(2)
iii. Why does corpus luteum stay active throughout pregnancy and in the absence of fertilization, is active only for 10-12 days?
OR
What happens to corpus luteum in human female if the ovum is (2)
a. fertilised,
b. not fertilised?

Early diagnosis is not possible by traditional methods for diagnosis and treatment- discuss in detail.

What is transgenic animals? How it is useful for man kind?

What is gene therapy? Illustrate using the example of adenosine deaminase (ADA) deficiency.

Draw a schematic diagram of typical anatropous ovule and describe structure of megasporangium in detail.###With a neat, labelled diagram, describe the parts of a typical angiosperm ovule.

Read the following text carefully and answer the questions that follow:
The following is the illustration of the sequence of ovarian events (A-I) in a humans female.

i. Identify the figure that illustrates ovulation and mention the stage of oogenesis it represents. (1)
ii. Name the ovarian hormone and the pituitary hormone that have caused the above mentioned event. (1)
iii. Explain the changes that occur in the uterus simultaneously in anticipation. (2)
OR
Write the differences between C and H. (2)

Describe tissue culture.