18. Genes and Inheritance

Question 1

What is a gene?

Answer 1

Gene is a part of a chromosome, the basic unit of inheritance. A length of DNA that controls a characteristic of an organism by coding for the production of a specific protein.

Question 2

What are Alleles?

Answer 2

Alleles are alternative forms of the same gene.

Question 3

What is a F1 generation?

Answer 3

F1 generation is an offspring formed from breeding the parent organisms

Question 4

What is a F2 generation?

Answer 4

F2 generation is an offspring formed from breeding individuals from the F1 generation

Question 5

What does dominant mean?

Answer 5

Dominant is an allele of a gene that is expressed in the heterozygote

Question 6

What does Recessive mean?

Answer 6

Recessive is an allele that is not expressed in the phenotype when a dominant allele of a gene is present in the heterozygote

Question 7

What is a phenotype?

Answer 7

Phenotype is the physical appearance or characteristics of an organism

Question 8

What is a homozygous?

Answer 8

Homozygous is having two identical alleles for a particular gene. e.g. AA or aa

Question 9

What is Heterozygous?

Answer 9

Heterozygous is having two different alleles for a particular gene. e.g. Aa

Question 10

What is a test cross?

Answer 10

Test cross is a cross of an organism showing the dominant phenotype with one showing the recessive phenotype. the F1 from the cross shows whether the parent is homozygous dominant or heterozygous

Question 11

What is a pedigree?

Answer 11

Pedigree is a diagram showing a family tree for an inherited characteristic

Question 12

What is Codominance?

Answer 12

Codominance is a pattern of inheritance where neither allele of a gene is dominant over the other so that both alleles are expressed in the phenotype

Question 13

What are sex chromosomes?

Answer 13

Sex chromosomes are a pair of chromosomes that determine sex in humans. XX in females and XY in males

Question 14

What is polygenic inheritance?

Answer 14

Polygenic inheritance are characteristics controlled by two or more genes working together

Question 15

What is a polygene?

Answer 15

Polygene is a name given to a group of several genes working together to determine a characteristic, e.g. height in humans.

Question 16

What are the rules of inheritance now known as?

Answer 16

The rules of inheritance are now known as ‘mendelian genetics’ in honour of gregor mendel who carried out the groundbreaking research that uncovered the rules of how genes are inherited.

Question 17

Who was gregor mendel?

Answer 17

Gregor Mendel was a monk who lived in a monastery in Brno. He became interested in the science of heredity, and carried out hundreds of breeding experiments using pea plants. from his research Mendel was able to explain the laws governing inheritance.

Question 18

What did Gregor Mendel find during his research?(5)

Answer 18

He found that for every feature or ‘character he investigated:
-A ‘heritable unit’ (gene) is passe from one generation to the next
-The heritable unit (gene) can have alternative forms (alleles)
-Each individual must have two alternative forms (alleles) per feature
-The gametes only have one of the alternative forms (allele) per feature
-One allele can be dominant over the other

Question 19

What is polydactyly?

Answer 19

Polydactyly is an inherited condition in which a person develops an extra finger on the hands and feet. It is determined by a dominant allele.