A dominant trait can be shown both when an organism is homozygous dominant AND heterozygous. Two different genotypes give the same visible result so a testcross is needed to be able to accurately say if the organism is homozygous dominant or heterozygous
Parasitism
Parasitism can be defined
as a relationship between species in which one organism (parasite) lives on or
in another organism which is the host, causing it some harm without immediately
killing it. Thus, parasitism is a kinds of close, symbiosis and persistent
biological interactions.
The answer is A.
Twins form in one of two ways:
Identical twins occur when a single fertilized egg splits into two.
Fraternal twins occur when two, separate eggs are fertilized by two, separate sperm.
Organ system that provides protectionfor the body and maintains homeostasis. (skin, hair, nails) Madeup of Epidermis & Dermis. Theoutermost, thin layer of skin, which contains proteins and is composed of 5 smaller layers of stratified squamous.
Answer:
A lot of factors cause genetic variation in a population. The root of all genetic variation is mutations, which occur randomly.
A lot of genetic variation in fact results during meiosis, the process by which gametes (sex/reproductive cells) are formed. The 3 main ways are crossing over, independent assortment of chromosomes, and random fertilization. Crossing over occurs during Prophase I of meiosis, in which genetic material is exchanged between nonsister chromatids of homologous chromosomes. Independent assortment refers to the following: When cells divide during meiosis, homologous chromosomes are randomly distributed during anaphase I, separating and segregating independently of each other. Random fertilization is where any sperm can fertilize any egg cell. The many combinations of eggs and sperms mean variation.
Another source of genetic variation include gene flow. Gene flow is where populations have their members enter other populations (migration), influencing the gene pool of populations. This source is more controversial, however.
Random mating can also increase genetic variation.
