Inheritance

Question 1

Gene

Answer 1

A sequence of DNA nucleotides that controls the formation of a single polypeptide . A unit of inheritance

Question 2

Inheritance

Answer 2

Transmission of traits from one generation to the next

Question 3

Alleles

Answer 3

Different form of the same gene
Occupy the same relative position on a pair of homologous chromosomes

Question 4

Genotype

Answer 4

Combination of alleles for a particular gene

Question 5

Phenotype

Answer 5

expressed trait

Question 6

Homozygous

Answer 6

Having two identical alleles of a particular gene

Question 7

Heterozygous

Answer 7

Having two different alle,es of a particular gene

Question 8

Codimnance

Answer 8

Both alleles express themselves in the heterozygote, which has a phenotype intermediate between that of its pure bred parents

Question 9

Variation

Answer 9

Difference in traits between Individuals of the same species

Question 10

Discontinuous

Answer 10

Clear cut phenotypes
Controlled by one or few gens
Genes do no show additive effect
Unaffected by environmental conditions

Question 11

Continuous

Answer 11

Range of phenotypes
Controlled by many genes
Genes show additive effect
Affected by environmental conditions

Question 12

Some source of genetic variation

Answer 12

Meiosis
Random fertilisation
Mutation

Question 13

Mutation

Answer 13

Change in sequence of genes or in chromosome number

Question 14

Albinism

Answer 14

Recessive gene mutation
Absence of pigment in skin hair and eyes
Sensitive to light and burnt easily

Question 15

Sickle cell anemia

Answer 15

Gene mutation > result in change in structure of gene > change in sequences of bases
Characteristics : encodes haemogoblin protein in RBC
Phenotype: ppl who are homozygous recessive have abnormal haemogoblin in RBC > oxygen council in blood decrease > RBC become sickle shakes

Question 16

Sickle shaped cells

Answer 16

Lose ability to transport oxygen .
Fragile sticky, stuck in narrow blood vessels > block flow of oxygen > fatal

Question 17

Natural selection

Answer 17

Process in which organism with desireable genes and characteristics are selected or favoured to survive and pass on their genes to their offspring

Question 18

Evolution

Answer 18

Gradual change I’m inheritable characteristics of a population over time

Question 19

Evolution by natural selection

Answer 19

Variation and competition for survival
Survival of fitest
Reproduction and passing down favourable genes

Question 20

How Mendel conducted his monohynrid experiment using pea plants. ( 3 steps )

Answer 20

1. Crossed ( cross pollinated ) tall pea plants with polllen from dwarf plants vice versa
2. Planted seeds the cross and observed traits of resulting offspring ( F1) > ALL TALL
3. Allowed F1 offspring to SELF FERTILISE and produce seeds which produce F2 with ratio of THREE tall plants and ONE dwarf

Question 21

Why does observed ratio often differ from expected ratio

Answer 21

1. Small sample size > not representative of actual population > inaccurate
2. Based on chance and probability > unlikely to match expected ratio precisely

Question 22

Differentiating dominant and recessive

Answer 22

If person has two DIFFERENT alleles, allele that express itself is called the DOMINNAT ALLELE, while other is called the recessive allele

Question 23

How can a recessive allele express itself

Answer 23

When person has BOTH recessive alleles in the gene ( e.g person with two alleles for single eyelid > have single eyelid )

Question 24

What do you use do describe an organism with two dominant alleles for a gene

Answer 24

That organism is homozygous dominant for the trait / gene

Question 25

What do you use do describe an organism with two recessive alleles for a gene.

Answer 25

That organism is homozygous recessive for the trait / gene

Question 26

When can a dominant allele express itself and give same phenotype