Enhancement of Food Production — BIOLOGY STD 12 Science — Question

Polyembryony.

The number of trophic levels in an ecosystem are limited. Comment.

List the three different allelic forms of gene “I” in humans. Explain the different phenotypic expressions, controlled by these three forms.

Give significance : Transgenic animals.

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

Justify the statements. If the answer is false, change the underlined word(s) to make the statement true.
(i) The DNA molecule is double stranded and the RNA molecule is single stranded.
Answer:

1. DNA as the genetic material has to be chemically and structurally stable.
2. It should be able to generate its replica.
3. Sugar-phosphate backbone and complementary base pairing between the two strands, give stability to DNA.
4. Both the strands of DNA act as template for synthesis of their complementary strands. This allows accurate replication of DNA.
5. Single stranded RNA can be folded to form complex structures and perform specific functions such as synthesis of proteins.

(ii) The process of translation occurs at the ribosome.

Define totipotency of a cell. List the requirements, if the objective is to produce somaclones of a tomato plant on commercial scale.

Hormones of adenohypophysis.

Your school’s athletic team along with the athletic teams from different schools reach the venue two days before the inter district school athletic event was to be held. A day before the competition, a team of officials from an agency arrive and ask for blood and urine samples from all the participating athletes.

1. Would you support or object to this sample collection? Provide explanation to your answer.
2. Write a note that you would like to read out to your team-mates to explain the purpose of this visit of these officials.