Correct Answer: Option 2 Gene expression can be influenced by the environment

Cloning is the process of producing populations of genetically-identical individuals that occurs in nature. If there would be variation, this is influenced by the environment in which the organisms are exposed to. For instance, a cloned shade-loving plant is exposed to sunlight, while the other clone is placed in a shaded area during growth stages. The clone exposed to sunlight might develop characteristics that would help it adapt to the intense light.

Meiosis is a two-staged type of cell division in sexually reproducing organisms. That results in gametes with half the chromosome number of the original cell. This causes variation of the offspring from the parent cells.

It is true that differentiated cells are dictated by different genes; but clones will undergo the same differentiation of cells. Hence, option 3 is incorrect.

If cloning is done to produce offsprings, the genetic composition of the parent is not divided but replicated to produce the same organism with the same genetic composition.

Correct Answer: Option 4 recombination of genes within the cell

Genetic recombination is the process by which a strand of genetic material (usually DNA; but can also be RNA) is broken and then joined to a different DNA molecule. In eukaryotes recombination commonly occurs during meiosis as chromosomal crossover between paired chromosomes. This process leads to offspring having different combinations of genes from their parents and can produce new chimeric alleles.

Variation may not be the effect of this kind of change. A change in the base subunit sequence could lead to an alteration of amino acid sequence to be coded to form the proteins of the body.

Evolution cannot take place because the recombination just happened in one organism, not it a population of organisms. Thus, the rate of evolution will not be affected.

Correct Answer: Option 2 genetic engineering

Genetic engineering, recombinant DNA technology, genetic modification/manipulation (GM) and gene splicing are terms that apply to the direct manipulation of an organism's genes. Genetic engineering is different from traditional breeding, where the organism's genes are manipulated indirectly. Genetic engineering uses the techniques of molecular cloning and transformation to alter the structure and characteristics of genes directly.

Options 1 and 2 are general terms to be used in the process. The traditional breeding can also be called as indirect sorting of genes. Thus, option 1 is invalid. During meiosis, there is recombination of genes. So option 2 is also not the precise answer.

Option 4 is incorrect. Mutation by deletion happens when a part of a chromosome or a sequence of DNA is missing. Any number of nucleotides can be deleted, from a single base to an entire piece of chromosome. Deletions can be caused by errors in chromosomal crossover during meiosis, not by intentional means. This usually causes genetic diseases.

Correct Answer: Options 3 and 6

Mutation in the ovary (structure 3) and in the testes (structure 6) might alter the genetic composition of the egg and sperm cells which will unite to form a zygote with mutated genes. The genome of the zygote contains all the genes needed to make the hundreds of different types of cells that will make up the complete animal. The mutated genes will be cause production of new alleles and will be carried out through generation and bring about evolution.

Structure 1 is the brain, while structure 3 is the ovary. Mutation in the brain might not introduce evolution because it will not be directly carried out by the individual to his next generation. This is also true for structures 2 (kidney), 4(liver), and 5(pancreas).

Correct Answer: Option 2 offspring were produced from different combinations of genes.

According to the studies of Gregor Mendel, alternative versions of gene (different alleles) account for variations in inherited characters. The laws of segregation (the two alleles of a character are packages into separate gametes) and independent assortment (each pair of allele segregates into gametes independenty) explain these variations.

There information given is insufficient to conclude variation due to adaptation. The habitat of the parents was the only information mentioned. This makes option 1 invalid.

Even though the parents were not exposed to mutagenic agents, they can still form different offspring because fish reproduce sexually. Hence, option 4 is incorrect.

Fishes reproduce sexually, thus variation occurs. Option 4 is incorrect.

Correct Answer: Option 1 skin cell and fertilized egg cell

Prior to sexual reproduction, the egg cell and sperm cell divide (meiosis) so the number of chromosomes is halved. When these cells unite, they retain the same number of chromosomes of each of the parents. Then all of the cells will become differentiated or specialized cells (e.g. kidney, skin, and liver cells) carrying the same number of chromosomes. Options 2, 3, and 4 are incorrect because the specialized cells have 26 chromosomes, while the egg or sperm cells only have 13 chromosomes. Option 1 is the correct answer because both the skin cell and the fertilized egg cell or zygote have 26 chromosomes.

Correct Answer: Option (3) 3

The two strands of DNA are anti-parallel. The nitrogenous bases have specific pairs. Thymine(T) pairs with adenosine (A). There are two blank boxes complementary of the two T bases, plus one given A. The total A bases in this DNA potion is three.

Cell A is a unicellular protist with a chloroplast, which is responsible for autotrophic nutrition. It absorbs sunlight and uses it to drive the synthesis of organic compounds from carbon dioxide and water.

Organelle X is the endoplasmic reticulum. It is an extensive network in eukaryotic cells (cell B is a plant cell), continuous with the outer nuclear membrane and composed of ribosome-studded and ribosome-free regions.

Correct Answer: Option 3 Both cell A and B use energy released from ATP.

Both cells undergo respiration, and thus produce ATP.

Option 1 is incorrect because both cells contain vacuoles.

Option 2 is incorrect. Both cells have nuclei. Therefore, DNA is present in both cells.

Option 4 is incorrect. Only the microorganism cell A can be a source of antibiotic.