Ecosystems and Energy Flow — BIOLOGY STD 12 Science — Question

1. Mention the specific geographical region where these organisms are found.
2. Name and explain the phenomenon that has resulted in the evolution of such diverse species in the region.
3. Explain giving reasons the existence of placental wolf and Tasmanian wolf sharing the same habitat.

Explain the following two components of Darwin's theory of natural selection.

1. Variations.
2. Formation of new species.

When a cross in made between tall plant with yellow seeds (TtYy) and tall plant with green seed (Ttyy), what proportions of phenotype in the offspring could be expected to be,

1. Tall and green.
2. Dwarf and green.

Explain xerarch succession highlighting the xeral communities.

Only asexual reproduction can give rise to individuals resembling their parent. Do you agree with the statement? Support your answer with an example.

Identify 'a', 'b', 'c', 'd', 'e' and 'f' in the table given below:

No.	Syndrome	Cause	Characteristics of affected individual	Sex Male/Female/Both
1	Down’s	Trisomy of 21	‘a’ (i) (ii)	'b'
2	‘c’	XXY	Overall masculine development	‘d’
3	Turner’s	45 with OX	‘e’ (i) (ii)	‘f’

What is Vasectomy? Represent it diagrammatically.

The genotypic ratio 1:2:2:4:1:2:1:2:1 is obtained in F₂ generation. What will be the phenotypic ratio?

Given below is the representation of amino acid composition of the relevant translated portion of B-chain of haemoglobin, related to the shape of human red blood cells.

1. Is this representation indicating a normal human or a sufferer from certain related genetic disease? Give reason in support of your answer.
2. What difference would be noticed in the phenotype of the normal and the sufferer related to this gene?
3. Who are likely to suffer more from the defect related to the gene representedthe males, the females or both males and females equally? And why?

Why do large animals cannot carry out respiration without the help of circulatory system?