EVOLUTION TEST

Question 1

​​​​D4.1.7- Sexual selection as a selection pressure in animal species.
- Outline the mechanism of sexual selection in evolution of courtship behavior and anatomical features. (AFS)

Answer 1

• Sexual Selection: individuals with certain inherited characteristics are more likely to obtain mates than other individuals
  Results in sexual dimorphism (differences between sexes in secondary sex characteristics)
  Size, color, ornamentation, behavior, etc.
  Intrasexual Selection: individuals of one sex (usually males) compete directly for mates
  Intersexual Selection: individuals of one sex (usually females) choose a mate
• Sexual Selection Occurs When Certain Traits Increase Mating Success; attractiveness to potential male, fertility of gametes, and successful rearing of offspring

Question 2

• Describe examples of sexual selection, including for color, size, and courtship behaviors.

Answer 2

• Some examples include the plumage (longer tails and deeper colour) in a peacock, which attracts mates, and the horns on a ram, which help it compete for a mate.
• birds of paradise; males exhibiting vast differences in behavior and an array of exotic feathers compared to females in order to attract them

Question 3

D4.1.8- Modelling of sexual and natural selection based on experimental control of selection pressures.
- Outline the selective pressures for and against coloration in guppies. (predators and mates)
- Summarize John Endler’s experiments with MALE guppies which demonstrate selection for and against coloration in different habitats.

Answer 3

• Spots that help the guppy blend in with its surroundings protect it from predation — but spots that make it stand out help it attract mates.
  After fewer than 15 generations of selection, the markings of guppies in different ponds had substantially diverged as a result of natural selection.
  Within waters filled with predators, the guppies were dull; when moved to waters with less dangerous predators, become more colourful; no predators in water, the guppies become extremely colourful

Question 4

FOR GUPPIES: sexual selection favours elaborate colours to attract females, but natural selection favours inconspicuous colours to avoid predation

• When there is a low predation rate, spot brightness on male guppies increases due to sexual selection
• As predation increases, the brightness of the spots decreases

Question 5

D4.1.9- Concept of the gene pool.
Define gene pool.
Describe how it is possible for multiple gene pools to exist in a single species.

Answer 5

Gene Pool: all the copies of every type of allele at every locus in all members of a population
- In diploid organisms, the gene pool is 2 times the number of alleles as there are individuals (each individual has 2 alleles)

Species can become geographically isolated resulting in the formation of multiple gene pools within a single species.

Question 6

D4.1.9- Concept of the gene pool.
Fixed Alleles:

Answer 6

Fixed Alleles: only one allele exits in the gene pool – all members of the populations are homozygous for this allele

Question 7

​​​​​​​D4.1.10- Allele frequencies of geographically isolated populations.
Define allele frequency.
Calculate allele frequency from gene pool data. (check example)

Answer 7

Allele frequency = measures how common allele is in population

Question 8

D4.1.11- Changes in allele frequency in the gene pool as a consequence of natural selection between individuals according to differences in their heritable traits.
- State that change in the allele frequencies of a gene is evidence of evolution.
- Explain how natural selection can lead to change in allele frequency in a gene pool.
- Outline “neo-Darwinism” as the integration of genetic inheritance and the mechanism of natural selection.​

Answer 8

• VOSB
• The fusion of Mendelian genetics and Darwin’s natural selection
• Darwin showed that evolution involves selection interacting with variation within populations
• Mendel that the bases of this variation are discrete units of heredity (genes)
• Natural selection therefore acts on heritable characteristics and through this certain characteristics are passed on within a species leading to adaptations

Question 9

D4.1.12- Differences between directional, disruptive and stabilizing selection.
- Outline the change in allele frequencies associated with stabilizing, disruptive and directional selection.
- Use graphs to illustrate or identify stabilizing, disruptive and directional selection.
- Outline an example of stabilizing, disruptive and directional selection.​

Answer 9

• Directional Selection: conditions favor one extreme of a phenotypic range
  Disruptive Selection: conditions favor both extremes of a phenotypic range
  Stabilizing Selection: conditions favor intermediates and select against extreme phenotypes
• EX:
  directional selection = long necks of giraffes
  disruptive selection = acorns/pepperred moths
  stabilizing selection = legs of rabbits (long legs are eliminated because the rabbits can’t crawl into a hole to escape predators, short legs are eliminated because they cannot run fast enough to escape predators.)

Question 10

D4.1.15- Artificial selection by deliberate choice of traits.
Define selective breeding and artificial selection.
Outline the mechanism of artificial selection in evolution of crop plants and domestic animals.
Describe an example of artificial selection of a crop plant or domestic animal.

Answer 10

• Artificial Selection: nature provides variation, and humans select variations that we find useful (domestic animals and crops)./A technique in which breeders select for a particular trait.
• Selective breeding leads to faster change than natural selection; this is because only the selected individuals are allowed to breed together, while in natural selection there will still be some breeding between individuals with less favourable alleles
• The next gen, will have an increased frequency of the desired allele and this process will continue until the entire generation has the desired trait.

Question 11

Explain why antibiotic resistance in bacteria is an example of natural selection.

Answer 11

• During the course of many years, certain bacteria have evolved and developed resistance to antibiotics due to overuse of antibiotics. (favorable inherited mutation)
• Antibiotics typically destroy bacteria, but some bacteria have a way of avoiding destruction
• Since this is a favoruable characteristic, only resistant bacteria will survive to reproduce and pass on their traits (including the one for resistance) to their offspring
• Eventually, the entire population is resistant to the antibiotic (adaptation)

Question 12

VARIATION WITHIN A SPECIES

Question 13

A3.1.1— Variation between organisms as a defining feature of life.
-Define organism.
-Define variation.
-List sources of genetic variation within a species. (MGMS)

Answer 13

• An organism is any biological system that functions as an individual life form.
• Variation refers to differences between members of a group.
• MUTATIONS/GENE FLOW/MEIOSIS/SEXUAL REPRODUCTION

Question 14

-Compare discrete and continuous variation.

Answer 14

Discrete - traits that can be put into qualitative categories/influenced by one or a few genes/not impacted too much by environment
Continuous - traits that vary along a quantitative continuum/influenced by multiple genes (polygenic)/impacted by environment.
Both types of variation

Question 15

-Compare variation within and between species.

Answer 15

• Variation within a species is called “intraspecies variation.” Genetic variation within a species is inheritable, meaning transmitted from parents to offspring.
• The amount of variation between individual organisms depends on how closely related they are to each other.
• Variation within: less variation/leads to evolution
• Variation between: more variation/doesn’t lead to evolution
• Both types of variation

Question 16

A3.1.2— Species as groups of organisms with shared traits.
- Define species according to the morphological species concept.

Answer 16

• According to the morphological species concept, a species is defined based on morphological characteristics, such as physical appearance, anatomy, and other observable traits.
• Organisms belonging to the same species share similar morphological features and can be distinguished from organisms of other species by these characteristics.
• Morphology = the clearly distinguishable shapes and forms of organisms.

LIMITATIONS:
- Genetically diverging populations may be hard to distinguish as unique species
- Morphologically similar groups may be the result of convergent evolution and not actually members of the same species.

Question 17

A3.1.3— Binomial system for naming organisms. Know that the first part of the name identifies the genus, with the second part of the name distinguishing the species. Species in the same genus have similar traits. The genus name is given an initial capital letter but the species name is lowercase.
- Define binomial nomenclature.
- State four rules of binomial nomenclature formatting.
- Outline why the binomial naming system is used in science rather than local names.

Answer 17

• two-name system of naming
• the first term indicates the genus; the second term indicates the specific species
• the genus name begins with a capital letter
  the species name begins with a lowercase letter
  in print, the name is in italics (underline if handwritten)
  after one use in a text, Genus name can be abbreviated to the first letter (i.e. H. sapiens)
• Reflects evolutionary relationships between organisms. All members of the same genus will share a common ancestor.
• Enables scientists to talk to each other in the same language. The same species can have many different local names so binomial nomenclature allows for consistency in communication around the world.

Question 18

Classifications (DKP COFGS)

Answer 18

DOMAIN
KINGDOM
PHYLUM
CLASS
ORDER
FAMILY
GENUS SPECIES

Question 19

A3.1.12— Difficulties applying the biological species concept to asexually reproducing species and to bacteria that have horizontal gene transfer.
- Compare sexual and asexual reproduction. (IGNORE)

Question 20

• Discuss difficulties in applying the biological species concept to asexually reproducing species such as dandelions.
• Define horizontal gene transfer.

Answer 20

• All offspring produced by asexual reproduction are clones of their parent, AS THEY ARE FORMED THROUGH MITOSIS.
• If a clone does not interbreed with other clones, it is a separate species according to the biological species concept.
• A better policy is to recognize that dandelions and other species that have abandoned sexual reproduction are no longer species according to the biological species concept.
• horizontal gene transfer: the introduction of genetic material from one species to another species

Question 21

how prokaryotes challenge biological species concept

Answer 21

• asexual reproduction; don’t meet criteria for interbreeding and fertile offspring b/c no exchange of genetic material through sexual reproduction
• experiences LOTS of variation; make it difficult to determine whether different strains represent distinct species or simply different variations of the same species
• Horizontal Gene Transfer: Prokaryotes often exchange genetic material through processes like conjugation, transformation, and transduction. This horizontal gene transfer means that genetic material can move between different species, blurring the boundaries of traditional species definitions.

Question 22

• Discuss difficulties in applying the biological species concept to bacteria that have horizontal gene transfer.

Answer 22

• This means that many organisms contain genetic information from species that are, evolutionarily speaking, only very distantly related, adding further complication to the attempt to classify organisms
• however, can classify base

Question 23

definitions

Answer 23

• Transformation is the alteration of a bacterial cell’s genotype by the uptake of naked, foreign DNA from the surrounding environment
• Transduction occurs when a bacteriophage (a virus that infects a bacterium) infects a bacterial cell and then transfers some of the cell’s DNA to another bacterium.
• Conjugation involves a direct physical interaction between two bacterial cells and the transfer of genetic material from a donor bacterium to a recipient bacterium

Question 24

sources of genetic diversity in bacteria

Answer 24

mutations & horizontal gene transfer

Question 25

D4.1.13- Hardy–Weinberg equation and calculations of allele or genotype frequencies.
- State the Hardy-Weinberg equations.
- Given data, calculate allele frequencies of genes in a gene pool.
- Given data, calculate genotype frequencies of genes in a gene pool.​

Answer 25

• Frequency of homozygous dominant: p x p = p2
  Frequency of homozygous recessive: q x q = q2
  Frequency of heterozygotes:
  (p x q) + (q x p) = 2pq
  Frequencies of all individuals must add to 1 (100%), so:
  p2 + 2pq + q2 = 1

Question 26

D4.1.14- Hardy–Weinberg conditions that must be maintained for a population to be in genetic equilibrium.
- List the conditions under which populations maintain Hardy-Weinberg equilibrium.
- Explain how comparison of allele frequencies between two isolated populations of the same species can serve as evidence that divergence is (or is not) occurring.
- Explain how comparison of allele frequencies between one population at two points in time can serve as evidence that evolution is (or is not) occurring.​

Answer 26

• No Mutations
  All Mating is Random (no preferences or inbreeding)
  No Natural Selection (all have equal chance of survival)
  Large Population Size (no genetic drift)
  No Gene Flow (alleles cannot enter or leave the gene pool)
• different allele frequencies - different selected for traits
• different allele frequencies

Question 27

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