ISC (Science) ISC Class 12 - CISCE Question Bank Solutions for Biology (Theory)

The diagram given below shows the various steps in spermatogenesis.

1. Name the parts labelled '1', '2' and '3'.
2. Name the process by which part '3' changes to part '4'.

State any four measures to control noise pollution.

What are the vestigial organs?

Give any one example of a vestigial organ in human body.

Assertion: Lymphocytes originate and proliferate in primary lymphoid organs.

Reason: Spleen is a secondary lymphoid organ.

Mention one significant difference between Hormones of ovulatory phase and hormones of luteal phase

Give a significant point of difference between the oestrous and menstrual cycles.

Define Amenorrhea

Briefly describe the secretory phase of the menstrual cycle.

Define: Menarche

Explain the role of hormones during the menstrual cycle.

Explain the process of sex determination in honey bees.

Given below is the diagram depicting the menstrual cycle in human beings. Study it carefully and answer the questions that follow.

1. Which phases are indicated by ‘C’ and ‘D’?
2. Name the structures labelled ‘F’. What is its role?
3. Explain the changes in the level of progesterone during phases ‘C’ and ‘D’.
4. Which hormone present in the urine confirms pregnancy in human beings?
5. Identify the structure labelled ‘E’. Name the hormone released by it.

Give a reason for the following:

The second half of the menstrual cycle is called the luteal phase as well as the secretory phase.

The diagram given below shows the three types of endosperms in angiosperms.

Type 1	Type 2	Type 3

1. Identify the three types of endosperms shown above.
2. Name the type of endosperm which commonly occurs in polypetalous dicots.

The number of chromosomes in the leaf cells of a male plant is 40 and in the stem cells of a female plant is 60. If they are artificially hybridised, what will be the number of chromosomes in the endosperm?

What are introns?

Transcription is the transfer of genetic code from a DNA molecule to ______.

Initiation codon of protein synthesis in Eukaryotes is ______.

What is the central dogma?