A molecule is a group of two or more atoms held together by chemical bonds. A compound is a substance which is formed by two or more different types of elements which are united chemically in a fixed proportion. All molecules are not compounds. All compounds are molecules.
DNA replication only happens during meiosis because the chromosome number of the species remains the same from one generation to the next, the chromosome number of germ cells must be reduced by half during meiosis. To achieve this feat, meiosis, unlike mitosis involves a single round of DNA replication followed by two rounds of cell division.
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: Photosythensis is the process in which green plants use sunlight to make their own food. ... Plants take in water from the soil and carbon dioxide from the air
Explanation:
