Genetics And Evolution

Step 1: Disruptive selection occurs when a homogeneous environment changes to a heterogeneous environment, leading to the formation of different types. This is the first statement and it is true.

Step 2: The second statement is incorrect because the frequency change of a gene due to chance and not selection in small populations is called genetic drift, not directional selection. Directional selection occurs when one extreme phenotype is selected, not when chance alone drives genetic changes. Thus, statement I is true, but statement II is false.

We are required to match the items from List I with those from List II.

Step 1: Let's analyze each option. Interferons are antiviral proteins that inhibit the replication of viruses, matching with option III.

Immunoglobulins are antibodies and are involved in recognizing foreign antigens and are associated with the paratope, so it matches with IV. Interleukins are proteins that stimulate immune cells such as T-cells and leukocytes, so they match with I. \item Tc-lymphocytes are associated with the production of perforins, which are cytotoxic proteins, so they match with II.

Thus, the correct answer is: (A) III, (B) IV, (C) I, (D) II.

Step 1: Monosomy refers to the condition where one chromosome from a pair is missing.

Step 2: Turner syndrome occurs when a female has only one X chromosome (45,X), which is an example of monosomy. The absence of one X chromosome leads to the condition known as Turner syndrome.

Step 1: Understanding Blood Group Inheritance
- Blood group A (homozygous) = AA
- Blood group B (homozygous) = BB
- Their offspring inherit one allele from each parent → AB.

Step 2: Possible Blood Groups in Children
- Offspring will have the AB blood group.
- A, B, and O blood groups are not possible.

Step 3: Conclusion
Since A, B, and O blood groups are not expected, the correct answer is Option (2).

Step 1: The presence of deleterious genes in a population, which may lower the fitness of individuals carrying them, is referred to as genetic load. It represents the burden of carrying harmful alleles in the gene pool of a population.
Step 2: Gene flow refers to the transfer of genetic material between different populations, while genetic drift is the random change in allele frequencies due to chance events, neither of which directly addresses the concept of harmful genes in a population.
Step 3: The Sewall Wright effect is a phenomenon where genetic variation in small populations changes due to random mating patterns and genetic drift, but it does not specifically relate to deleterious genes.
Thus, the correct answer is Genetic load.