Differential 3.1

Question 1

What was Gregor Mendel’s pea-plant experiment and what was its aim? (1 sentence each)

Answer 1

• Mendel cross-pollinated pea plants based on their different features such as texture, colour, and stem length
  including smooth or wrinkled ripe seeds,
• He aimed to discover how traits are inherited between generations

Question 2

What three important discoveries did Mendel make?

Answer 2

1. The Law of Segregation: offspring acquire one hereditary factor from each parent
2. The Law of Independent Assortment: different traits have an equal opportunity of
   occurring together (this was later shown to not entirely be true)
3. The Law of Dominance: offspring will inherit the dominant trait, and can only inherit the recessive trait if they inherit both recessive factors

Question 3

What is the definition of genotype and phenotype?

Answer 3

A genotype is a unique sequence of DNA. It is two alleles inherited for a particular gene

Phenotype is the detectable expression of this genotype - what we see

Question 4

What are dominant and recessive traits? (1 sentence each)

Answer 4

Dominant traits are expressed when the connected allele is dominant, even if only one copy of it exists.

Recessive traits are expressed only if both connected alleles are recessive.

Question 5

What is meant by Mendelian inheritance? (1 sentence)

Answer 5

Traits caused by a single gene with two alleles and inherited in a predictable way

Question 6

What are three characteristics of continuous variation and what are three examples?

Answer 6

Unbroken range of phenotypes in a population
Many genes contribute
Environmental factors affect gene expression
E.G. height, weight, and skin color

Question 7

What are four characteristics of discontinuous variation and what are three examples?

Answer 7

• Two or more distinct phenotypes for a particular characteristic in a population
• Most simple type of genetic variation
• One gene with two alleles - dominant allele exhibit one phenotype while recessive exhibits the second phenotype
• Predictable relationship between the genotype and phenotype
  E.G. flower colour, blood groups, gender

Question 8

What is the definition of heritability, and what are two important characteristics of it? (1 sentence and 2 points)

Answer 8

The proportion of population variance attributed to genetic influences
- Does not apply to individuals
- Is not a property of a characteristic, refers only to genetics relative to the total variance in populations

Question 9

What are the definitions of ‘shared environment’ and ‘non-shared environment’? (1 sentence each)

Answer 9

Shared = environmental
factors actually acting to make household members more similar
Non-shared = environmental factors that act to make household members different, and to measurement error