Biology Test - 70

The meiosis has two stages of division, meiosis I & meiosis II which are reductional & equational divisions respectively. The first meiotic division leads to the reduction of the chromosome number to half i.e haploid condition, the second meiotic division results in the formation of four different daughter cells which are haploid in number, it provides a physical basis for the law of segregation and independent assortment.

So, the correct answer is"For the segregation of replicated chromosomes".

The concept was proposed by George Beadle and Edward Tatum in an influential 1941 paper on genetic mutations in the mold Neurospora crassa, and subsequently was dubbed the "one gene–one enzyme hypothesis" by their collaborator Norman Horowitz.

A crtoss used to ascertain whether a dominant is homozygous or heterozygous is termed back cross.

Epistasis is a phenomenon that consists of the effect of one gene being dependent on the presence of one or more 'modifier genes'. Similarly, epistatic mutations have different effects in combination than individually. It was originally a concept from genetics, but is now used in biochemistry, population genetics, computational biology and evolutionary biology. It arises due to interactions, either between genes, or within them leading to non-additive effects. Epistasis has a large influence on the shape of evolutionary landscapes which leads to profound consequences for evolution and evolvability of traits.

Prokaryotes are unicellular organisms without membrane-bound organelles. They lack a true nucleus. Instead, they have nucleoid, a genetic material without the nuclear envelope. In prokaryotes, the genetic material is single circular double-stranded DNA without histones

While many parts of the body make hormones, the major glands that make up the endocrine system are the:

• hypothalamus.
• pituitary.
• thyroid.
• parathyroids.
• adrenals.
• pineal body.
• the ovaries.
• the testes.

Lion fish are noted for their venomous fin spines, which are capable of producing painful, though rarely fatal, puncture wounds.

Banding pattern of present man chimpanzee is nearly the same. It indicates that both haveevolved from common stock.