Life Science: Genetics

Question 1

What are the 3 Mendel’s Laws?

Answer 1

• Law of Segregation
• Law of Independent Assortment
• Law of Dominance

Question 2

Q: What is a Genotype?

Answer 2

A: A Genotype is a DNA sequence that carries an allele for a trait.

Question 3

Q: What is a Phenotype?

Answer 3

A: A Phenotype is a physical characteristic that can be observed.

Question 4

Q: What is a Dominant allele?

Answer 4

A: A dominant allele is the phenotype that is expressed over the recessive allele.

Question 5

Q: What is a Recessive allele?

Answer 5

A: A Recessive allele is a phenotype that will only be expressed if both recessive alleles are on the homologous chromosomes.

Question 6

Q: Describe a Homozygous Dominant chromosome.

Answer 6

A: A homozygous dominant contains two dominant alleles.
Ex: AA

Question 7

Q: Describe a Heterozygous chromosome.

Answer 7

A: A heterozygous chromosome contains both a dominant & recessive allele. Ex: Aa

Question 8

Q: Describe a Homozygous Recessive chromosome

Answer 8

A: A homozygous recessive chromosome contains two recessive alleles. Ex: aa

Question 9

Name the three ways that lead to genetic variation

Answer 9

• Random Fertilization (random combo of sperm and egg)
• Independent assortment during Meiosis I (metaphase I; shuffles whole chromosomes)
• Crossing over during meiosis I (prophase I; shuffles segments of chromosomes)

Question 10

How does random fertilization lead to genetic variation?

Answer 10

A zygote is a combination of the DNA of two different people.

Question 11

How does independent assortment lead to genetic variation?

Answer 11

Each gamete contains a unique set of gene from the parent.

Question 12

How does crossing over lead to genetic variation?

Answer 12

Homologous chromosomes swap DNA with one another, meaning that is gamete is genetically unique.

Question 13

A plant has a gene for flower color where the flower can be either red or white. The red color is dominant and white is recessive. Two heterozygous plants are crossed. What percentage of offspring will have a homozygous dominant genotype?

Answer 13

25%

Question 14

The blood groups A and B are both dominant for the same allele. Which of the non-Mendelian inheritance does this represent?

Answer 14

Codominance

Question 15

Which mechanism of evolutions specifies that species change over time in response to their environment?

Answer 15

Natural selection

Question 16

Under which conditions would Mendel’s law not apply?

Answer 16

PIGS C
- Polygenic traits
- Incomplete dominance
- Gene linkage
- Sex-linked genes
- Codominance

Question 17

______ is described as changes in a population and species over time.

Answer 17

Evolution

Question 18

When would a dihybrid cross be utilized?

Answer 18

Used for two individuals that differ in two traits of interest.
- Ex: AaBb x AaBb

Question 19

What are polygenic traits? provide an example of polygenic traits.

Answer 19

Traits that are influenced by multiple genes rather than a single gene
- Ex: Skin color, Height

Question 20

What is gene linkage?

Answer 20

Genes located close to each other on the same chromosome are inherited together during meiosis, affecting inheritance patterns

Question 21

What is codominance? provide an example of codominance.

Answer 21

non-Mendelian genetics where two or more alleles can be dominant, and both expressed., resulting in a phenotype that shows both traits
- Ex: AB blood type

Question 22

What is incomplete dominance? provide an example of incomplete dominance

Answer 22

non-Mendelian genetics where heterozygous genotype leads to a mixed phenotype
-> Ex: Homozygous Dominant red flower (RR) and Homozygous recessive (rr) white flower create a heterozygous flower that is pink.

Question 23

what are sex-linked genes? Provide an example of sex-linked genes.

Answer 23

non-Mendelian genetics where genes are located on sex chromosomes that are inherited differently in males and females, leading to ex-linked traits and disorders.

Question 24

When would non-mendelian inheritance patterns occur?

Answer 24

They would occur when there are factors other than dominant & recessive traits.