Unit Test #2

Question 1

What are linked genes?

Answer 1

Genes on the same chromosome.

Question 1

What is the definition of a gene?

Answer 1

Sequence of DNA which codes for a specific protein.

Question 2

Describe transcription.

Answer 2

Copies information from gene to a sequence of RNA.

Question 3

Describe translation.

Answer 3

Converts RNA sequence to amino acid sequence

Question 4

What is the definition of a genotype?

Answer 4

Actual sequence of DNA within an individual’s cell.

Question 5

What is the definition of a phenotype?

Answer 5

The individual observable traits or characteristics.

Question 6

Describe the way a mutation happen.

Answer 6

Wrong pairing of nitrogenous bases during DNA replication (or transcription)➡️different DNA strand➡️different mRNA strand➡️different codon➡️different amino acids➡️different amino acid sequence➡️different protein➡️different observable trait.

Question 7

Explain the difference between homozygote and heterozygote alleles.

Answer 7

Homozygote: identical alleles
Heterozygote: different alleles

Question 8

What is the difference between monohybrid and dihybrid?

Answer 8

Monohybrid: heterozygous for one gene

Dihybrid: heterozygous for 2 genes.

Question 9

Explain the difference between domine and recessive allele. Explain homozygous dominant.

Answer 9

Dominant: Allele which is ALWAYS expressed ➡️ Capital Letters

Recessive:
Allele whose phenotype can be masked by a dominant allele ➡️ lowercase letter

Homozygous dominant: 2 dominant alleles.

Question 10

What are the types of inheritance?

Answer 10

Allele effects:
-Complete dominance
-Multiple alleles
-Co-Dominance
-Incomplete Dominance
-Pleiotropy

Gene effects:
-Epistasis
-Multiple genes
-Environmental Interactions
-Multifactorial Interactions

Genes and Chromosomes:
-Linked Genes
-Sex Chromosomes

Question 11

Explain the difference between incomplete dominance and co-dominance.

Answer 11

Incomplete: mix or blent
Co-Dominance: See phenotype separately.(blood)

Question 12

What is the definition of multiple alleles?

Answer 12

A given gene may have more than two alleles.

Question 13

Explain pleiotropy.

Answer 13

A single allele can have multiple effects, especially on distant and unrelated phenotypes

Question 14

Explain epistasis.

Answer 14

Phenotypic expression of one gene is influenced by another gene

Question 15

Explain polygenic inheritance.

Answer 15

It’s the result of combined effect of several genes.

Question 16

What is the definition of natural selection? Give me some characteristics of it.

Answer 16

Differential contribution of offspring to the next generation by various genetic types belonging tot the same population.

Characteristics:
-Act on phenotype
-Act on individuals
-Variation MUST be heritable

Question 17

What is the definition of evolution? Give me some characteristics of it.

Answer 17

A change in allele frequencies over time within a population.

Characteristics:
-Act on phenotype
-Act on individuals
Population evolves not individuals (change in allele frequencies over time)

Question 18

What is the definition of the evolutionary fitness?

Answer 18

Genetic contribution that an organism makes to the next generation and to the generation thereafter.
It’s an actual quantity that can be measured or calculated.

Question 19

Explain directional selection.

Answer 19

It favorises individuals that vary in one direction

Question 20

Explain stabilizing selection.

Answer 20

It favorises individuals that have the average version of the trait.

Question 21

Explain disruptive selection.

Answer 21

It favorises individuals that demonstrate either extreme version of the trait.

Question 22

Explain sexual selection and its two types.

Answer 22

The sex that spend the most time on the offspring is more picky. It favorises traits that increase the chances of reproduction.

Intersexual selection: more attractive to opposite sex
Intrasexual: improve ability to compete for mates.

It leads to sexual dysmorphism and male/female differences.

Question 23

Explain microevolution.

Answer 23

Allele frequency change over time→ easy to prove

Question 24

Explain adaptation.

Answer 24

Evolution of adaptive trait.

Question 25

Explain macroevolution and how to see it.

Answer 25

Large phenotypic changes.

Many many years:
-Fossils
-Extinction
-Transitional forms

Question 26

What is the difference between a bottleneck and the founder effet.

Answer 26

Bottleneck: a lot of dying
Founder effect: start new population

Question 27

Explain genetic drift.

Answer 27

Random changes in allele frequencies in a population due to random nature of sexual reproduction.

Question 28

Explain speciation.

Answer 28

Process by which one species splits into two or more daughter species, often gradually.

Question 29

Name species concept and describe them.

Answer 29

Morphological species:
-Look alike, but:
-Males and females don’t look alike
-Immature individuals may not look like parents

Biological species:
-Species are groups of actually or potentially interbreeding natural populations which are reproductively isolated form other such groups.

Question 30

What are the modes of speciation?

Answer 30

Allopatric
Sympatric
Prezygotic
Postsygotic

Question 31

Explain allopatric speciation.

Answer 31

Reproductive isolation and divergence often physical separation.

Question 32

Explain sympatric speciation.

Answer 32

-Reproductive isolation and divergence while populations are not physically separated.
-Disruptive selection
-Sexual selection

Question 33

Explain the different types of prezygotic selection.

Answer 33

1-Behavioral selection:
-Individuals reject or fail to recognize potential mating partners.
Habitat isolation:
2-Individuals mate in different locations.
3-Temporal isolation:
Mating periods don’t overlap.
4-Mechanical isolation:
Difference in sizes and shapes of reproductive organs.
5-Gametic isolation:
Eggs don’t have appropriate chemical signals for sperm or sperm unable to attach and to penetrate egg.

Question 34

Explain the different types of postzygotic selection.

Answer 34

1-Low hybrid zygote viability:
Fail to mature or have severe abnormalities.
2-Low hybrid adult viability:
Lower survival rate
3-Hybrid infertility:
Offspring are healthy and viable, but infertile.