Polygenic Inheritance and Continuous Variation in Human Traits

The video tutorial explains the concept of polygenic inheritance using skin color distribution as an example. It highlights that traits like skin color, height, and eye color are controlled by multiple genes, leading to continuous variation. The tutorial uses wheat kernel color to illustrate how dominant and recessive alleles contribute to phenotype expression through additive effects. A Punnett square is used to demonstrate these genetic combinations. The video also emphasizes the role of environmental factors in trait expression, particularly in human skin color.

What is the main difference between skin color and flower color in Mendel's pea plants?

• Skin color is a discrete trait, while flower color shows continuous variation.

• Flower color in pea plants is influenced by the environment, unlike skin color.

• Skin color shows continuous variation, unlike the discrete flower color in pea plants.

• Skin color is controlled by a single gene, while flower color is not.

Which of the following traits is NOT an example of polygenic inheritance?

• Height

• Eye color

• Blood type

• Skin color

In the context of polygenic inheritance, what does 'additive effects' refer to?

• The effect of environmental factors on gene expression.

• The dominance of one allele over another.

• The combined effect of multiple genes on a single trait.

• The influence of a single gene on multiple traits.

In the wheat kernel color example, what color is produced when all alleles are recessive?

• Pink

• Light red

• Dark red

• White

What happens to the kernel color when there is one dominant allele and one recessive allele?

• The kernel turns light red.

• An intermediate pinkish color is produced.

• The kernel turns dark red.

• The kernel remains white.

How does the number of dominant alleles affect the kernel color in wheat?

• Dominant alleles only affect the size of the kernel.

• The number of dominant alleles has no effect on kernel color.

• More dominant alleles result in a lighter kernel color.

• More dominant alleles result in a darker kernel color.

What is the purpose of using a Punnett square in the context of polygenic inheritance?

• To determine the environmental influence on a trait.

• To visualize the combinations of alleles and their effects on a trait.

• To calculate the exact number of dominant alleles.

• To identify the recessive alleles in a genotype.

What does a bell curve in the graph of phenotypes indicate?

• A random distribution of traits.

• No variation in traits.

• A continuous variation of traits.

• A discrete variation of traits.

Which factor, besides genes, plays a significant role in the expression of polygenic traits?

• Age

• Diet

• Gender

• Environment

How does exposure to sunlight affect human skin color?

• It darkens the skin color.

• It lightens the skin color.

• It has no effect on skin color.

• It changes the skin color to red.