Inheritance

Question 1

Variation

Answer 1

are the differences between individuals of the same species

Question 2

Continuous Variation

Answer 2

results in a range of phenotypes between two extremes

Question 3

Discontinuous Variation

Answer 3

results in a limited number of phenotypes with no intermediates

Question 4

Gene

Answer 4

a segment of DNA that codes for a specific protein

Question 5

DNA

Answer 5

Deoxyribonucleic acid - controls cells functions by controlling the production of proteins

Question 6

Inheritance

Answer 6

the transmission of genetic information from generation to generation

Question 7

Allele

Answer 7

an alternative form of a gene

Question 8

Genotype

Answer 8

The genetic make-up of an organism in terms of the alleles present

Question 9

Phenotype

Answer 9

are the features of an organism that are expressed due to an organism’s genotype

Question 10

Homozygous

Answer 10

means having two identical alleles of a particular gene

Question 11

Heterozygous

Answer 11

means having two different alleles of a particular gene

Question 12

Dominant

Answer 12

one allele of a heterozygous individual that will be dominant therefore will be expressed

Question 13

Recessive

Answer 13

one/two alleles of an individual that will be recessive therefore will only be expressed if there is no dominant allele present

Question 14

Codominance

Answer 14

neither alleles are dominant to one another and so both are expressed

Question 15

Mutation

Answer 15

Mutations are spontaneous genetic changes in the way new alleles are formed.

Question 16

Genetic Mutations

Answer 16

Are random changes in the base of the DNA

Question 17

Chromosome Mutations

Answer 17

Are the changes in the chromosome number or structure

Question 18

Reasons for Genetic Mutations

Answer 18

One or more genes may not be copied correctly
Ex: Sickle celled anaemia

Question 19

Sickle celled anemia

Answer 19

The distortion and destruction of the red cells, which occurs in low oxygen concentrations lead to bouts of severe anemia.

Question 20

Reasons for Chromosome Mutations

Answer 20

Loss of a part of a chromosome, or damage to it during mitosis or meiosis, or joining of an extra chromosome
Ex: Down Syndrome (47 chromosomes instead of 46 chromosomes)

Question 21

Down’s syndrome

Answer 21

Down’s syndrome is a form of mental and physical disability, this is caused by the fact that the zygote has 47 chromosomes instead of 46 chromosomes.

Question 22

Effects of Mutations

Answer 22

It may result in a defective enzyme and will usually
disrupt the complex reactions in the cells. Most
mutations, therefore, are harmful to the organism but there are some beneficial mutations for the success of the organism

Question 23

Junk DNA

Answer 23

Are repeated sequences of nucleotides that do not code for proteins and have functions that are unknown.

Question 24

Mutation in somatic cell

Answer 24

It may give rise to cancers because mutations stimulate uncontrolled cell division and only affects the cells produced by the mutant cells.
Ex. Skin cancers

Question 25

Mutations in gametes

Answer 25

A mutation in a gene may result in a genetic disorder and affects the whole organism.
Ex. Cystic fibrosis

Question 26

Mutations in junk DNA

Answer 26

If mutations occur in these non-coding sequences they are unlikely to have any effect on the organism

Question 27

Reasons for genetic variations in populations

Answer 27

Genetic mutation, meiosis, random mating, and random fertilization

Question 28

Causes that increase the rate of mutations

Answer 28

Exposure to some chemicals, ionizing radiation, radioactive compounds and ultra-violent compounds

Question 29

Reasons for bacterial mutations to happen in colonies

Answer 29

Bacterial cells reproduce very rapidly so as a result, a mutation is likely to appear in a large population of bacterial cells.

Question 30

What will happen if the population of drug-resistant bacteria gets exposed to the drug?

Answer 30

The antibiotic will not kill the bacteria with drug resistance, unlike the non-drug-resistant bacteria.

Question 31

Adaptive feature

Answer 31

Is an inherited feature that helps an
organism to survive and reproduce in its environment.

Question 32

Natural Selection

Answer 32

• Variations are individuals within a species slightly different from each other.
• If the individual possesses some adaptive feature of variation for the struggle of survival including competition for resources, they are more likely to survive than others.
• If one variety lives longer than others, it is also
  likely to leave behind more offspring with the adaptive feature.
• If some of the offspring inherit alleles responsible
  for the variation that helped the parent survive
  better, they too will live longer and have more
  offspring.
• Eventually this particular variety will outnumber and finally, replace the original variety

Question 33

Adaptation

Answer 33

Is the process, resulting from natural selection,
by which populations become more suited to their
environment over many generations

Question 34

Evolution

Answer 34

Can be described as the change in adaptive features of a population over time as a result of natural selection

Question 35

Example of Natural selection

Answer 35

MRSA (an antibiotic-resistant bacteria)

Question 36

Antibiotics

Answer 36

Are drugs used to treat infections caused
by bacteria

Question 37

Development of Antibiotic-resistant bacteria

Answer 37

Bacterial cells reproduce very rapidly, thus if a mutation is to occur, it is likely to appear in a large population of bacteria. When the surviving mutant bacteria reproduce, all their offspring will be resistant to the drug.

Question 38

Artificial Selection (Selective breeding)

Answer 38

• The process of selective breeding involves humans selecting individuals with desirable features.
• These individuals are then cross-bred to produce the next generation.
• Offspring with the most desirable features are chosen to continue the breeding program
• The process is repeated over a number of generations.

Question 39

Role of artificial selection

Answer 39

• Animal breeders will select cows for their high milk yield and sheep for their wool quality.
• Plant breeders will select varieties for their high yield and resistance to fungus diseases