Answer:
Explanation:
Mechanical digestion physically breaks down food, like when teeth macerate food into a bolus. The stomach contracts and relaxes in a churning motion. ... Chemical digestion occurs when the bonds within larger food molecules are broken, creating smaller molecules that the body can use.
Answer:
the answer is D.
Explanation:
The heritable variation is defined as the variance of the breeding values among individuals.
Scanning electron microscope- this is a type of microscope that uses beams of electrons to view the surface of a specimen. it is used to provide a three-dimensional image of cells
transmission electron microscope- uses beams of electrons to examine the insides of thin slices of materials. it is used to provide a two-dimensional image of cell structures
2and3 only are the defense
Answer AND Explanation:
<u>FACTORS THAT CAUSE GENETIC VARIATIONS</u>
- Crossing over. At the chiasmata during prophase I of meiosis, breakage may occur and exchange of genetic information may take place. New gene combinations which result in variations.
- Independent assortment. The arrangement of homologous chromosomes at the equator of the spindle during metaphase of the first meiotic division is random. These homologous chromosomes segregate into different daughter cells which contain different genetic combinations which brings about variation
- Fertilisation permits parental genes to be brought together in different combinations. This is the cause of variations in members of the same family.
- Mutation is the spontaneous change in the genetic makeup of an organism. These changes may be inherited by the offspring therefore beginning variation.
