20.1 Variation and inheritance

Question 1

What is chlorosis? (2 marks)

Answer 1

Cells in plant leaves don’t produce enough chlorophyll, so they appear yellow, this results in reduced photosynthesis.

Question 2

State 3 environmental factors that can cause chlorosis. ( 3 marks)

Answer 2

Lack of light
Mineral deficiencies
Virus infections

Question 3

Is chlorosis affected by genetics or the environment or both? (1 mark)

Answer 3

Both

Question 4

What is a genotype? (1 mark)

Answer 4

The combination of alleles an organism inherits for a characteristic.

Question 5

What is a phenotype? (1 mark)

Answer 5

The observable characteristic of an organism.

Question 6

What is a dominant allele? (1 mark)

Answer 6

A version of the gene that will always be expressed if present in the organism.

Question 7

What is a recessive allele? (1 mark)

Answer 7

Will only be expressed if there are two copies of the allele are present in the organism.

Question 8

What is meant by a homozygous genotype? (1 mark)

Answer 8

Two identical alleles for a charcteritic.

Question 9

What is meant by a heterozygous genotype? (1 mark)

Answer 9

Two different alleles for a characteristic.

Question 10

What is discontinuous variation? (1 mark)

Answer 10

Individuals fall into distinct groups.

Question 11

What is continuous variation? (1 mark)

Answer 11

There are two extremes and then a range in between.