chapter 9

Question 1

Achromatopsia

Answer 1

an inherited form of total colour blindness

Question 2

Albinism

Answer 2

an inherited inability to produce pigment in hair, skin and eyes.

Question 3

Allele frequency

Answer 3

how often each allele of a gene occurs in a population

Question 4

anaemia

Answer 4

a condition in which there is a reduced amount of haemoglobin in the blood, or reduced number of red blood cells.

Question 5

Aneuploidy

Answer 5

a change in the chromosome number as a result of non-disjunction

Question 6

Bottleneck effect

Answer 6

an extreme form of genetic drift that occurs when the size of a population is severely reduced due to a sudden event such as a national disaster. The allele frequency of survivors may not reflect that of the original population.

Question 7

Chromosomal mutation

Answer 7

a change to the structure and/or number of chromosomes in an organism

Question 8

Cri-du-chat syndrome

Answer 8

a rare genetic disorder caused by a missing part of chromosome 5.

Question 9

Cystic fibrosis

Answer 9

a disorder controlled by a recessive allele carried on an autosome that is incurable but can be detected during foetal development ; mucus-secreting glands, particularly in the lungs and pancreas, become fibrous and produce abnormally thick mucus, resulting in chest infections

Question 10

Down syndrome

trisomy 21

Answer 10

a genetic disorder resulting from an extra copy of chromosome 21 or an extra part of chromosome 21.

Question 11

Duchenne muscular dystrophy

Answer 11

a genetic disease resulting in wasting of leg muscles and then arms, shoulders and chest.

Question 12

Evolution

Answer 12

the gradual change in the characteristics of a species

Question 13

Evolved

Answer 13

having gone through the process of evolution

Question 14

Founder effect

Answer 14

a type of genetic drift where a new population is formed by a small number of individuals; the small sample size can cause marked deviations in allele frequencies from the original population.

Question 15

frameshift

Answer 15

a mutation involving an insertion of a deletion that results in a change in the way that the sequence is read.

Question 16

Gene flow

Answer 16

the transfer of alleles from one population to another through migrations.

Question 17

Gene mutation

Answer 17

an alteration to a single gene.

Question 18

Gene pool

Answer 18

the sum of all the alleles carried by the members of a population.

Question 19

Genetic drift

Answer 19

also random genetic drift

the occurrence of characteristics in a population as a result of chance rather than natural selection;
occurs only in small populations; also called genetic drift or Sewall Wright effect.

Question 20

Geneticist

Answer 20

a scientist who specialises in the study of genetics

Question 21

Genotype

Answer 21

The combination of allele for a gene

Question 22

Geographical barrier

Answer 22

a feature of the landscape that prevents populations from interbreeding; includes oceans, mountain ranges, large lake systems, deserts and extensive ice sheets.

Question 23

germinal or germline mutation

Answer 23

a change in the hereditary material in the egg or sperm that becomes incorporated into the DNA of every cell in the body of the offspring.

Question 24

Heterozygote advantage

Answer 24

a situation where heterozygous genotype has a higher chance of survival that either homozygous geneotype.

Question 25

Induced mutation

Answer 25

a mutation caused by a mutagenic agent

Question 26

Klinefelter syndrome

Answer 26

A genetic disorder resulting from inheritance of two X chromosomes and one Y chromosome.

Question 27

Lethal recessive

Answer 27

a recessive allele that inherited in the homozygous condition results in the death of the embryo, foetus or child.

Question 28

Migration

Answer 28

the movement of people from one area to another with the intention of settling permanently.

Question 29

Missense mutation

Answer 29

a mutation that causes a change in an amino acid resulting in a different protein l=being produced.

Question 30

Monosomy

Answer 30

where an individual has only one copy of a chromosome instead of two.

Question 31

Mutagen, mutagenic agent

Answer 31

an environment agent that increases the rate of mutations

Question 32

Mutant

Answer 32

an organism with a characteristic resulting from a mutation

Question 33

Mutation

Answer 33

a change in a gene or chromosome leading to new characteristics in an organism.

Question 34

Natural Selection

Answer 34

the process by which a species becomes better adapted to its environment. Those individuals with favourable characteristics have a survival advantage and so pass those characteristics on to subsequent generations

Question 35

Neutral mutation

Answer 35

a mutation that causes a change in an amino acid, however it does not cause an overall change in the protein.

Question 36

Nonsense mutation

Answer 36

a mutation that results in a STOP cpdon, producing a shortened peptide chain.

Question 37

Partial monosomy

Answer 37

where part of a pair of chromosomes is missing

Question 38

Patau syndrome

Answer 38

a genetic disorder resulting from an extra copy of chromosome 13.

Question 39

Phenotype

Answer 39

the observable characteristic due to the genotype.

Question 40

Phenylketonuria PKU

Answer 40

an inherited disease resulting in damage to the growing brain and, thus, extreme intellectual deficiency. Also a tendency for epilepsy and a failure to produce skin pigmentation.

Question 41

Point mutation

Answer 41

a change in just one of the bases in a DNA molecule.

Question 42

Population

Answer 42

a group of organisms of the same species living together in a particular place at a particular time.

Question 43

Selective agent

Answer 43

any factor that causes the death of organisms with certain characteristics, but which has no effect on individuals withour those characteristics.

Question 44

Sickle cell anemia

Answer 44

an inherited disease causing early death. | results from the inheritance of two alleles for sickle-cell anemia.

Question 45

Silent mutation

Answer 45

a mutation that does not change the sequence of amino acids.

Question 46

Sociocultural barrier

Answer 46

barrier to interbreeding that is due to social or cultural factors.

Question 47

Somatic mutation

Answer 47

a change occurring in a gene in a body cell. (not a gamete- ova or sperm)

Question 48

Special creation

Answer 48

the belief that a god created all species.

Question 49

Speciation

Answer 49

the process of new species developing

Question 50

Species

Answer 50

the basic unit of biological classification; members of a species are capable of interbreeding and producing fertile offspring.

Question 51

Spontaneous mutation

Answer 51

a mutation that occurs due to an error in a natural biological process.

Question 52

Struggle for existence

Answer 52

a principle where the number of organisms is greater than the resources in the environment can support. Therefore there is competition between the organisms for resources

Question 53

Survival of the fittest

Answer 53

a principle whereby organisms with favourable characteristics survive. Organisms with unfavourable characteristics die before they have a chance to reproduce

Question 54

Tay-Sachs disease tsd

Answer 54

a genetic disorder caused by a missing enzyme that results in fatty substances accumulating in the nervous system.

Question 55

Turner syndrome

Answer 55

a genetic disorder resulting from inheritance of one X chromosome and no other sex chromosome

Question 56

variation

Answer 56

the difference that exist between individuals or populations of a species.