Ecosystems — BIOLOGY STD 12 Science — Question

A cross was carried out between a pea plant heterozygous for round and yellow seeds with a pea plant having wrinkled and green seeds.

1. Show the cross in a Punnett square.
2. Write the phenotype of the progeny of this cross.
3. What is this cross known as? State the purpose of conducting such a cross.

What is DNA finger printing. Who discovered it. Write the DNA finger printing process. Writes its uitility.

Pistil of a flower does not accept pollen from any plant other than from its own kind. How does it happen? Explain.

Shown above is the electron micrograph (EM) picture of 'beads-on-string'.

1. Identify and explain the detailed structure of a bead with the help of a labelled diagram.
2. Describe the packaging of 'beads-on-string'in a eukaryotic cell.

Differentiate between microsporogenesis and megasporogenesis. Which type of cell division occurs during these events? Name the structures formed at the end of these two events.

What is pisciculture? Write its role in improving quality of food.

Describe in detail the development of male gametophyte in angiosperms with well labelled diagram.

Write any four ways used to introduce a desired DNA segment into a bacterial cell in recombinant technology experiments.

a. Why did Hershey and Chase use radioactive ³²P and ³⁵S in their experiments? Explain.
b. Following the experiments conducted by them, write what conclusion did they arrive at and how.

1. Write an equation for Verhaulst-Pearl Logistic Growth, where.

N - Population density at a timet E.

r - Intrinsic rate of natural increase.

K - Carrying Capacity.

2. Draw a graph for a population whose population density has reached the carrying capacity.
3. Why is this logistic growth model considered a more realistic one for most animal populations?
4. Draw a growth curve where resources are not limiting to growth of a population.