Sexual Reproduction in Flowering Plants — BIOLOGY STD 12 Science — Question

What is cancer? Write the main types of cancer. Name at least three deadly signs of cancer.

Define ecological pyramids and describe with examples, pyramids of number and biomass.

When and where are primary oocytes formed in a human female? Trace the development of these oocytes till ovulation (in menstrual cycle). How do gonadotropins influence this developmental process?

What is the significance of epididymis in male fertility?

Read the following and answer any four questions from (i) to (v) given below:
Transgenic animals can serve as factories that in some cases, may produce large amount of proteins more efficiently. Transgenic mice have been engineered to express human antibodies by introducing large segment of human DNA encoding human immunoglobulin genes. In transgenic large animals such as cow or sheep proteins of pharmaceutical value can be produced in large quantities in milk which is later purified. Transgenesis can be used to alter many phenotypic properties including growth rate, fat composition, milk production, hair texture, etc.

1. The production of transgenic animals includes

1. Identification and separation of desired gene.
2. Combining the desired gene with appropriate vector.
3. Introduction of vector in cells, tissues or embryos.
4. All of these.

2. In transgenic animals, i.e., cow and sheep proteins of pharmaceutical value are produced in large quantities in the

1. Blood.
2. Accumulated fat.
3. Mammary glands.
4. None of these.

3. Mouse is mostly preferred animal for studies on gene transfer because.

1. Short oestrous cycle.
2. Long gestation period.
3. Short generation time.
4. Production of one or two offspring per pregnancy.

1. Both (A) and (C)
2. Both (A) and (B)
3. Only D
4. Both (C) and (D).

4. Transgenic genes alter many phenotypic properties including:

1. Growth rate.
2. Fat composition.
3. Milk production.
4. All of these.

5. Assertion: Transgenic mice have been engineered to express human antibodies.

Reason: Large segment of human DNA encoding human immunoglobulin have been transferred to mice.

1. Both assertion and reason are true and reason is the correct explanation of assertion.
2. Both assertion and reason are true but reason is not the correct explanation of assertion.
3. Assertion is true but reason is false.
4. Both assertion and reason are false.

The following is the illustration of the sequence of ovarian events (a – i) in a human female.
Write the difference between ‘c’ and ‘h’.

Write a short note on electronic waste. List the various sources of e-wastes and the problems associated with its disposa

Write notes on ex-situ conservation of biodiversity

Mukta visits a dairy farm near her locality to buy milk for her household. While, waiting there for her turn, she noticed that one of the member of the farm was injecting something into the cow before milking. She was very curious and discussed her queries with her friend (a biology expert).

1. What did the injection contain?
2. Why is this injection administered to the cow?
3. State any two methods of herd impre vement.
4. What values are shown by Mukta?

In case of polyembryony, If one embryo develops from the synergid and another from the nucellus, which one is haploid and which is diploid? Describe polyembryony and also mention how can it be commercially exploited.