biology_flashcards_topic7

Question 1

What is a genotype?

Answer 1

The genetic constitution of an organism.

Question 2

What is a phenotype?

Answer 2

The expression of the genotype and its interaction with the environment.

Question 3

What are alleles?

Answer 3

Different versions of a gene, arising by mutation.

Question 4

How many alleles of a gene can be found in diploid organisms?

Answer 4

Two alleles, one from each homologous chromosome.

Question 5

What is a dominant allele?

Answer 5

An allele that is always expressed in the phenotype.

Question 6

What is a recessive allele?

Answer 6

An allele that is only expressed when two copies are present.

Question 7

What is codominance?

Answer 7

Both alleles are expressed in the phenotype when present together.

Question 8

What does homozygous mean?

Answer 8

Both alleles at a locus are the same.

Question 9

What does heterozygous mean?

Answer 9

The alleles at a locus are different.

Question 10

What is a monohybrid cross?

Answer 10

A cross that studies the inheritance of one characteristic controlled by a single gene.

Question 11

What is a dihybrid cross?

Answer 11

A cross that studies the inheritance of two characteristics controlled by two different genes.

Question 12

What is a sex-linked gene?

Answer 12

A gene located on a sex chromosome, usually the X chromosome.

Question 13

Why are males more likely to express recessive X-linked alleles?

Answer 13

Because they only have one X chromosome; they lack a second allele that could be dominant.

Question 14

What is autosomal linkage?

Answer 14

When genes are located on the same autosome and tend to be inherited together.

Question 15

What is epistasis?

Answer 15

Interaction of non-linked genes where one gene masks the expression of another.

Question 16

When is the chi-squared test used in genetics?

Answer 16

To compare observed and expected phenotypic ratios.

Question 17

What is a population?

Answer 17

A group of organisms of the same species in a given place at a given time.

Question 18

What is a gene pool?

Answer 18

All the alleles of all the genes in a population at a given time.

Question 19

What is allele frequency?

Answer 19

The proportion of a specific allele in a gene pool.

Question 20

What is the Hardy-Weinberg principle?

Answer 20

Allele frequencies remain constant across generations if certain conditions are met.

Question 21

List the Hardy-Weinberg conditions.

Answer 21

Large population, no migration, no mutation, random mating, no selection.

Question 22

What is the Hardy-Weinberg equation?

Answer 22

p² + 2pq + q² = 1.

Question 23

What is evolution?

Answer 23

A change in allele frequency over time in a population.

Question 24

What are selection pressures?

Answer 24

Factors like predation, disease, and competition that influence survival.

Question 25

What is stabilising selection?

Answer 25

Selection that favours average phenotypes.

Question 26

What is directional selection?

Answer 26

Selection that favours one extreme phenotype.

Question 27

What is disruptive selection?

Answer 27

Selection that favours both extremes of a phenotype.

Question 28

What is speciation?

Answer 28

The formation of new species from existing species.

Question 29

What is allopatric speciation?

Answer 29

Speciation due to geographical isolation.

Question 30

What is sympatric speciation?

Answer 30

Speciation without geographical isolation, due to reproductive barriers.

Question 31

What is genetic drift?

Answer 31

Change in allele frequencies due to chance, especially in small populations.

Question 32

What is a community?

Answer 32

All the populations of different species in an area at a given time.

Question 33

What is an ecosystem?

Answer 33

A community plus its abiotic environment.

Question 34

What is a niche?

Answer 34

The role of a species in its habitat, including what it eats and how it interacts with others.

Question 35

What is carrying capacity?

Answer 35

The maximum stable population size an environment can support.

Question 36

Name factors affecting carrying capacity.

Answer 36

Abiotic factors, interspecific competition, intraspecific competition, predation.

Question 37

How does interspecific competition affect population size?

Answer 37

Reduces availability of resources, possibly leading to decline.

Question 38

How does intraspecific competition affect population size?

Answer 38

Population cycles around carrying capacity due to resource availability.

Question 39

Explain predator-prey cycles.

Answer 39

Predator and prey populations fluctuate cyclically, with predators lagging behind prey.

Question 40

How do you estimate a population of non-motile organisms?

Answer 40

Random quadrats, counting, and scaling up.

Question 41

How does the mark-release-recapture method work?

Answer 41

Capture, mark, release, recapture, then calculate with the formula.

Question 42

What is succession?

Answer 42

Changes in a community over time due to changes in abiotic and biotic factors.

Question 43

What is a climax community?

Answer 43

A stable community with relatively constant populations.

Question 44

How does conservation manage succession?

Answer 44

By preventing later stages to maintain biodiversity.

Question 45

What is random sampling?

Answer 45

Using random coordinates to place quadrats to avoid bias.

Question 46

Why is a large sample size important?

Answer 46

It reduces the impact of anomalies and increases accuracy.

Question 47

What is systematic sampling?

Answer 47

Sampling along a transect to study gradients.

Question 48

What is the statistical test for correlation?

Answer 48

Spearman's rank correlation coefficient.

Question 49

What is an example of a pioneer species?

Answer 49

Lichens or mosses that colonize bare rock.

Question 50

Why is biodiversity higher in later succession stages?

Answer 50

Increased habitat variety supports more species.

Question 51

What is the founder effect?

Answer 51

A small group starts a new population with reduced genetic diversity.

Question 52

What is the bottleneck effect?

Answer 52

A sharp reduction in population size reduces genetic diversity.

Question 53

What is independent segregation?

Answer 53

Random separation of homologous chromosomes during meiosis.

Question 54

What is crossing over?

Answer 54

Exchange of alleles between homologous chromosomes during meiosis.

Question 55

What is random fertilization?

Answer 55

Random union of gametes, increasing variation.

Question 56

What is the role of mutation in evolution?

Answer 56

Provides new alleles for selection to act on.

Question 57

What is the difference between natural selection and genetic drift?

Answer 57

Natural selection is due to advantage; drift is due to chance.

Question 58

What is a quadrat?

Answer 58

A square frame used to sample non-motile organisms.

Question 59

What is a transect?

Answer 59

A line along which sampling is done to study environmental gradients.

Question 60

What is a test cross?

Answer 60

Crossing an individual with a homozygous recessive to determine its genotype.

Question 61

What is an example of a sex-linked disease?

Answer 61

Haemophilia or colour blindness.

Question 62

What is codominance in blood groups?

Answer 62

IA and IB alleles both expressed, giving AB blood group.

Question 63

Why might observed ratios differ from expected ratios?

Answer 63

Random chance, small sample size, linkage, epistasis, lethal alleles.

Question 64

How can one detect autosomal linkage?

Answer 64

Deviation from expected ratios in dihybrid crosses.

Question 65

Why is large sample size important in Hardy-Weinberg?

Answer 65

To minimise the effect of random genetic drift.

Question 66

What are the two types of speciation?

Answer 66

Allopatric and sympatric.

Question 67

How does crossing over affect inheritance?

Answer 67

It can break linked genes and create new allele combinations.

Question 68

What is plagioclimax?

Answer 68

A community maintained at an earlier stage of succession by human activity.