Biology Test 155

Phenotype of an organism is the result of genotype and environmental interactions.

Phenotype, all the observable characteristics of an organism that result from the interaction of its genotype (total genetic inheritance) with the environment. Examples of observable characteristics include behaviour, biochemical properties, colour, shape, and size.

Hence, the correct option is (D).

Male and female flowers are present on different plants (dioecious) to ensure Xenogamy in papaya. 

In Xenogamy, the anther and filaments constitute stamen which is the male part of the flower. During the cross-fertilization, the ovum from one individual is fused with the spermatozoa of the other. It involves cross-fertilization between unrelated individuals that lead to the masking of deleterious recessive alleles in the given progeny. Cross-pollination involves certain characteristics that facilitate the pollination that includes herkogamy which is to avoid self-pollination by bearing a mechanical barrier on the stigmatic surface. The maturation of the Pollen on the stigma of the flower at different times which is to avoid self-pollination. n certain flowers, the mature Pollen falls on the receptive stigma which fails to bring self-pollination on the same flower. Male sterility is another characteristic that facilitates cross-pollination as the pollen grains are not functional.

Hence, the correct option is (A).

Synthetic auxins are employed for killing weeds.

Synthetic auxins like 2, 4-D, and 2, 4, 5-T are used as herbicides. A 2, 4-D stands for 2,4-Dichlorophenoxyacetic acid. It is a plant growth regulator. It is used as a weedicide. It kills the broadleaf weeds that harm the plants by causing uncontrolled growth in them.

Hence, the correct option is (C).

Basis of taxonomy are Classification - Characterization - Identification - Nomenclature.

Study of lawful arrangement of organisms is called Taxonomy. Taxonomy based on the four aspects, namely Characterization, Identification, Nomenclature, Classification.

Hence, the correct option is (C).

Eutrophication in the Chesapeake Bay along the eastern edge of Maryland has resulted in low oxygen levels in the water and alternation of food webs. The cause of this eutrophication appears to be pollution that contains high levels of nitrogen and phosphorus.

Scientists have recognized that nutrient enrichment was a threat to the bay. In 1987 formal goals were established to reduce nitrogen and phosphorous inputs to the bay from both point and non point sources.

Hence, the correct option is (B).

Cell wall in higher plants is made up of cellulose and pectin.

The plant cell derives its shape from its cell wall. The plant cell wall contains a complex sugar cellulose which is a structural carbohydrate that gives protection and supports the plant. In the case of higher plants, cellulose and pectin are chief components. The primary cell wall is composed of cellulose, hemicellulose and pectin. Pectin is also found in middle lamella which helps the binding of cells.

Hence, the correct option is (B).

If an angiospermic male plant is diploid and female plant tetraploid, the ploidy level of endosperm will be pentaploid.

Polyploidy is the condition which has more than two sets of chromosomes. If an angiospermic male plant is diploid and female plant is tetraploid, the ploidy level of endosperm will be pentaploid because the female gametes undergoes meiosis and forms gametes (2n). This female gametes (2n + 2n of polar nuclei) fuses with the male gametes (n).

Hence, the correct option is (D).

80% C₂H₄ and 20% CO₂ combination of gases is suitable for fruit ripening.

80% ethylene and 20% CO₂ is the optimum composition for the ripening of fruits. Ethylene is the gas which helps in artificial ripening. Ethylene promotes flowering of plants. It also promotes senescence.

Hence, the correct option is (A).

UAG, UGA–Stop pairs of codons is correctly matched with their function or the signal for the particular amino acid.

The genetic code contains the full information of the protein produced from RNA. It is the order of base pairs of amino acids that code for protein to be manufactured. Thus a change during this sequence can alter the formation of amino acids. UAG, UGA – Stop is a pair of codons that are correctly matched with their function or the signal for the particular amino acid. There are three stop codons, which are UAG, UGA, and UAA. They are nonsense or terminating or stop codons as these are responsible for the termination of translation. They indicate the release of the nascent polypeptide from the ribosome because no like tRNA has anticodons complementary to those stop signals, enabling a release factor to bind to the ribosome rather. These do not code for any amino acid.

Hence, the correct option is (B).

Aldolase is found in cytoplasm.

The process of glycolysis takes place in the cytoplasm and aldolase is the important enzyme for glycolysis. Therefore aldolase is found in the cytoplasm. The enzyme is found in all cells and is most common in the brain, liver tissues, and muscles. ALDOA is an enzyme that is vital for the 4th step of glycolysis and the reverse pathway gluconeogenesis. The higher amount of aldolase results in liver damage or a sign of muscle damage. Aldolase blood test is to diagnose and monitor the conditions related to skeletal muscles. Aldolase B is found in the liver. It is also present at the lower levels in kidney and intestinal cells.

Hence, the correct option is (C).