Variation and inheritance

Question 1

What is variation

Answer 1

differences between animals interspecies and intraspecies - arise as a result of mutation, changes to the genetic code which are random and constantly taking place

Question 2

What is chlorosis

Answer 2

leaves on plants look pale or yellow as their cells are not producing a normal amount of chlorophyll pigment

Question 3

Causes of chlorosis: lack of light

Answer 3

plants turn of their chlorophyll production in absence of light in order to conserve resources

Question 4

Causes of chlorosis: mineral deficiencies

Answer 4

lack of iron (cofactor on some enzymes that make chlorophyll) and magnesium (found at the heart of the chlorophyll molecule)

Question 5

Viral infections

Answer 5

viruses interfere with metabolism of cells affecting chlorophyll production

Question 6

Body mass as a result of genetic makeup

Answer 6

mutation on chromosome 7 - causes the pattern of fat deposition in the body to be altered. This gene acts in conjunction to other genes that regulate the energy balance of the body

Question 7

How do we inherit combinations of alleles from our parents

Answer 7

determined by sexual reproduction involving meiosis (formation of genes) and random fusion of gametes at fertilisation - causes variation within species

Question 8

What is genotype

Answer 8

alleles we possess as individuals/ genetic constitution of an organism

Question 9

What is phenotype

Answer 9

the physical characteristics of an individual often affected by the environment

Question 10

What is an allele

Answer 10

a version of a gene

Question 11

Homozygous

Answer 11

two of the same allele

Question 12

Heterozygous

Answer 12

two different alleles

Question 13

Monohybrid

Answer 13

one gene being determined

Question 14

Dihybrid

Answer 14

two genes are combined (e.g hair colour and hair length)

Question 15

Dominant allele

Answer 15

version of the gene that will always be expressed if present in an organism (TT: blue eyes, Tt: Blue eyes tt: green eyes)

Question 16

Recessive allele

Answer 16

will only be expressed if there are two copies of the same allele (homozygous recessive)

Question 17

what is continuous variation

Answer 17

there are two extremes, with every degree of variation possible in between (e.g height or weight)

Question 18

what is discontinuous variation

Answer 18

individuals fall into distinct groups and normally only one gene is involved, the environment as very little affect on this (e.g eye colour, hair colour, blood group)

Question 19

Homozygous genetic cross

Answer 19

Mendel carried out crosses between homozygous yellow pea pot plants and homozygous green pea pot plants - all of the offspring are heterozygous which means all F1 will be green but have the genotype Gg

Question 20

Heterozygous genetic cross

Answer 20

taking heterozygous offspring from the F1 and crossing them - F2 generation are produced and have a 3:1 ratio of green to yellow pea pod plants (GG, Gg, Gg, gg)

Question 21

what is codominance

Answer 21

when two different alleles occur for a gene - both of which are equally dominant and so both are expressed in the phenotype of the organism (e.g if there is an allele that codes for red flowers/pigment and one that codes for white/no pigment they will be pink and so heterozygous