Nat5 Biology Unit 2 Multicellular Organisms Key Area 4 Variation And Inheritance

Question 1

What is a Gene?

Answer 1

A gene is a section of DNA that codes for a species that codes for a specific protein. It is the unit of heredity, and can be copied and passed on to the next generation

Question 2

What does P/F1/F2 mean?

Answer 2

Parents/ First generation of offspring / second generation

Question 3

What is a Phenotype?

Answer 3

The appearance/characteristic of an organism e.g. tongue roller, albino

Question 4

What is a Genotype?

Answer 4

The genetic make_up of an organism, indicated by two symbols e.g. “TT” , “aa”

Question 5

What is the genotype of a gamete?

Answer 5

The genetic make-up pf the gamete, indicated by one symbol e.g. “T” , “a”

Question 6

What are Alleles?

Answer 6

The different forms of a gene, e.g. “A” and “a” are Alleles for the gene of albinism, while “T” and “t” are the Alleles for the gene for tongue rolling

Question 7

What is Homozygous (True breeding)

Answer 7

The two Alleles are the same e.g. “TT” or “tt”, ”AA” or “aa”

Question 8

What is Heterozygous (Hybrid)

Answer 8

The two Alleles are different e.g. “Tt” or “Aa”

Question 9

What is a Dominant gene?

Answer 9

The allele that shows in the phenotype of the heterozygote, e.g. “Tt” is a tongue roller, so the tongue rolling Allele must be dominant over the non-roller Allele

Question 10

What is a Recessive gene?

Answer 10

The Allele that is masked in the heterozygote e.g. “Aa” has normal pigmentation, so the Allele for albino must be recessive

Question 11

What is Polygenic Inheritance?

Answer 11

Several genes are involved in the inheritance of a characteristic. This means there is a range of phenotypes showing continuous variation e.g.. heights and skin colour in humans, mass of seeds in plants. There’s a maximum, and a minimum. Polygenic inheritance is responsible for most features of an organism’s phenotype

Question 12

What is Monohybrid Inheritance?

Answer 12

A single gene controls a phenotype, e.g. attached ear lobes/unattached ear lobes. This will result in discrete variation. Measurements fall into distinct groups

Question 13

What is Discrete Variation?

Answer 13

Discrete variation is where measurements fall into distinct groups or categories.

Question 14

What graph do we use to show discrete variation?

Answer 14

A bar graph

Question 15

What type of inheritance is it that measurements fall into distinct groups?

Answer 15

Single gene inheritance

Question 16

What is continuous variation?

Answer 16

Continuous variation is where a characteristic can have any value over a range, from minimum to maximum.

Question 17

What graph do we use to show continuous variation?

Answer 17

A histogram

Question 18

What type of inheritance is it that shows continuous variation?

Answer 18

Polygenic inheritance

Question 19

How does variation occur?

Answer 19

Combining genes from two different parents

Question 20

At so we use to explain inheritance?

Answer 20

Punnett squares

Question 21

Why are predicted phenotype ratios among offspring not always achieved?

Answer 21

Fertilization is a rAnDoM pRoCeSs