Nucleic acid<span> typically contain phosphorous, and nitrogen plays an important structural role in nucleic acids and proteins. The proteins, being made up a diverse set of amino acids, have, in addition to carbon, hydrogen, oxygen, and nitrogen, the elements sulfur and selenium.</span>
<span>Point mutations are of two types: Substitutions of bases that are the change of one base of DNA by another. And Transitions that are replaced on a pyrrhic basis by another pyrrhic or a pyrimidine by another pyrimidine. Transversions: substitution of a pyrrhic base by another pyrimidine or vice versa. These mutations are negative because they affect only one of the nucleotides, and therefore, only one triplet of bases are affected. When the mutation does not affect the individual it is a silent mutation. Chromosomal mutations Changes in the structure of the diploid chromosomes, where one of the chromosomes has a mutation, will have another normal. They can hinder the process of meiosis in the carrier since it hinders the correct pairing of the homologous chromosomes. It would produce an unfeasible offspring or with mutations.</span>
Answer: Substances that are protein based cannot cross the lipid cell membrane, but can exert their effect by binding to the proteins based receptors present on the lipid bilayer.
Explanation:
Hormones such as calcitonin , Parathyroid hormone and pituatry horomones are proteins and water soluble.They cannot cross lipid bilayer but can bind to ligand binding protein receptors.
These receptors are protein macromolecules that are specific in nature for specific hormones.
After binding to the receptors, these hormone-recpetor complexes activate second messengers and regulate the downstream effects.
Answer:
B
Explanation:
Cooling reduces the excitement of the molecules of the DNA hence allowing the hydrogen bonds between the base pairs of the two strands to form hence the DNA is considered to anneal. Heating disrupts the hydrogen bonds and causes the two strands to dissociate.
Answer: d. All the above
Fertilizers can be deterimental to the environment. Excess use of fertilizers will result in eutrophication in the water body. Water body being more enriched with nutrients will result in excessive growth of aquatic plants. This also result in algal bloom in which algae grows on the surface of water body because of this atmospheric oxygen not able to reach the aquatic plants, hence results in oxygen depletion.
