Human Reproduction — BIOLOGY STD 12 Science — Question

A non–haemophilic couple was informed by their doctor that there is possibility of a haemophilic child be born to them. Explain the basis on which the doctor conveyed this information. Give the genotypes and the phenotypes of all the possible children who could be born to them.

Match Column I with Column II.

S. No.	Column I	S. No.	Column II
A.	Acrosome	1.	Motility of sperm towards the egg.
B.	Head	2.	Powerhouse of the sperm; contains a number of mitochondria.
C.	Tail	3.	Contains the genetic material.
D.	Middle piece	4.	Contains enzymes to dissolve egg envelopes.

1. A tRNA is charged with the amino acid methionine.

1. Name the process involved in the attachment.
2. Point out the mRNA codon and anticodon on RNA for this amino acid.

2. What is heterochromatin?

1. Differentiate between analogous and homologous structures.
2. Select and write analogous structures from the list given below:

1. Wings of butterfly and birds.
2. Vertebrate hearts.
3. Tendrils of bougainvillea and cucurbita.
4. Tubers of sweet potato and potato.

Mention the advantages of selecting pea plant for experiment by Mendel.

1. Identify the polarity at A and B respectively in the figure given below.
2. Explain the mechanism the figure represents.

Pollen banks are playing a very important role in promoting plant breeding programme the world over. How are pollens preserved in the pollen banks? Explain. How are such banks benefitting our farmer? Write any two ways.

Study the given pedigree chart and answer the questions that follow:

1. Is the trait recessive or dominant?
2. Is the trait sex-linked or autosomal?
3. Give the genotypes of the parents shown in generation I and their third child shown in generation II and the first grandchild shown in generation III.

Differentiate between two different types of pyramids of biomass with the help of one example of each.

Describe the three different types of IUDs available at present, with an example for each.