7.1 - Inheritance

Question 1

What does heterozygous mean?

Answer 1

Describes an individual where both alleles of a gene are different

Question 2

What is a sex chromosome?

Answer 2

Chromosomes that contain genes that determine the sex of an organism

Question 3

What is the genotype of an organism?

Answer 3

The genetic constitution of an organism, the total combination of alleles an organism has inherited and carries on its chromosomes.

Question 4

Define diploid

Answer 4

A cell containing half the number of chromosomes

Question 5

What is a recessive allele?

Answer 5

An allele that is not expressed in the phenotype of heterozygous organisms

Question 6

What is an allele?

Answer 6

Different forms of a particular gene, found at the same locus on a chromosome. A single gene could have many alleles.

Question 7

What is a homologous pair?

Answer 7

Two chromosomes containing the same genes at the same loci but potentially containing different alleles

Question 8

Define haploid

Answer 8

A cell containing half the diploid number of chromosomes

Question 9

What is the phenotype of an organism?

Answer 9

Observable or measurable features of an organism which are the result of the genotype as well as environmental factors

Question 10

What is a zygote?

Answer 10

A diploid cell formed from fusing two haploid nuclei

Question 11

Define recessive

Answer 11

An allele only expressed in homozygous individuals and the characteristic is only expressed if there is no dominant allele present.

Question 12

Define dominant

Answer 12

An allele that is expressed in the phenotype of heterozygous organisms

Question 13

What is an autosome?

Answer 13

Chromosomes that are not sex determining chromosome

Question 14

What is a sister chromatid?

Answer 14

Identical copies of a chromosome formed in DNA replication. Containing the same alleles in the same locations

Question 15

What is a gene?

Answer 15

A length of a DNA coding for the production of a polypeptide or protein and occupying a specific locus on a chromosome

Question 16

Define homozygous

Answer 16

Describes an individual where both alleles of a gene are the same

Question 17

What is DNA?

Answer 17

A polynucleotide chain

Question 18

What is a chromatin?

Answer 18

Loosely packed molecule of DNA and proteins

Question 19

What is a chromatid?

Answer 19

One half of a duplicated pair of chromosomes (sister chromatids)

Question 20

What is a chromosome?

Answer 20

A structure that forms when chromatin condenses

Question 21

What does codiminant mean?

Answer 21

Both alleles are expressed equally and contribute to the phenotype, with there being either a blend of the two characteristic or both characteristics being seen together.

Question 22

What is a locus?

Answer 22

The specific position of the gene on the chromosome.

Question 23

What is pure breeding?

Answer 23

Homozygous pair of alleles.

Question 24

What is sex linkage?

Answer 24

Sex linkage is the expression of an allele dependent on the sex of the individual as the gene is located on the sex chromosome.

Question 25

What is an autosomal linkage?

Answer 25

In an autosomal linkage two or more genes are on the same autosomal chromosome

Question 26

What is recessive epistasis?

Answer 26

Occurs when the presence of a recessive allele prevents the expression of another allele at a second locus. 9:3:4

Question 27

What is dominant epistasis?

Answer 27

When a dominant allele at one locus completely makes the alleles at a second locus. 12:3:1

Question 28

What is monohybrid inheritance?

Answer 28

When a phenotype or trait is controlled by a single gene. For instance, cystic fibrosis is where the individuals with doubly recessive phenotype are affected.

Question 29

What is dihybrid inheritance?

Answer 29

When two characteristics are studied and is determined by two different genes that are present on two different chromosomes at the same time.

Question 30

What is an example of codiminance?

Answer 30

Human ABO blood groups.