KS3 Biology

Question 1

In humans what is the name of the female sex cell?

Answer 1

Egg cell

Question 2

In humans what is the name of the male sex cell?

Answer 2

Sperm cell

Question 3

When an egg cell and a sperm cell fuse: ________

Answer 3

Fertilisation

Question 4

Gow many chromosomes are in the nucleus of a normal human body cell?

Answer 4

46

Question 5

How is DNA arranged?

Answer 5

Into strands called chromosomes

Question 6

What is a gene?

Answer 6

A section of a chromosome that controls a particular characteristic.

Question 7

What does DNA stand for?

Answer 7

Deoxyribonucleic acid

Question 8

How many forms of each gene do we inherit?

Answer 8

Two (called alleles)

Question 9

What is the function of the cell membrane?

Answer 9

To control what enters and leaves the cel

Question 10

What is the function of the nucleus of a cell?

Answer 10

To contain the DNA (chromosomes)

Question 11

What is an allele?

Answer 11

An allele is a different form of a gene. (e.g the alleles for an eye colour gene could be brown, blue, green, etc.)

Question 12

What does the phrase “homozygous alleles” mean?

Answer 12

If an individual has 2 identical alleles for a characteristic

Question 13

What does the phrase “heterozygous alleles” mean?

Answer 13

If an individual has 2 different alleles for a characteristic

Question 14

What sex chromosomes has a male inherited?

Answer 14

XY

Question 15

What sex chromosomes has a female inherited?

Answer 15

XX

Question 16

How many chromosomes are in the nucleus of a human sex cell?

Answer 16

23

Question 17

What are the 2 types of phenotype (physical expression of our alleles) variation?

Answer 17

Genetic and environmental

Question 18

Scars - environmental or genetic variation?

Answer 18

Environmental

Question 19

Blood group - environmental or genetic variation?

Answer 19

Genetic

Question 20

What ks a genetic disorder?

Answer 20

A diseased caused by a faulty gene or chromosome

Question 21

What is a recessive genetic disorder?

Answer 21

A genetic disorder carried on a recessive allele. The individual has inherited a faulty allele from each parent.

Question 22

What is a dominant genetic disorder?

Answer 22

A genetic disorder carried on a recessive allele. The individual has inherited a faulty allele from at least one parent.

Question 23

What is selective breeding?

Answer 23

Choosing two organisms with a desirable characteristic to breed, as their offspring will likely have the same characteristic.

Question 24

What is the process of selective breeding?

Answer 24

1. Choose two parents with the desired characteristic
2. Breed them together
3. Choose offspring that show the desired characteristic and breed them.
4. Repeat over many generations.

Question 25

What are the disadvantages of selective breeding?

Answer 25

1. Can lead to inbreeding 2. Genetic pool gets smaller leading to more harmful recessive alleles to be passed on 3. Offspring are more susceptible to diseases

Question 26

What are the advantages of selective breeding?

Answer 26

1. Increased yield (e.g more milk/meat from cattle, larger crops for food) 2. Disease resistance in food crops or plants 3. Produce domestic animals with a desired characteristic (e.g docile/territorial) 4. More decorative plants 5. New varieties of crops

Question 27

What is a GMO?

Answer 27

Genetically modified organism

Question 28

What happens in gneetic engineering?

Answer 28

Genes of an organism are changed by introducing a gene from another organism to give a desired characteristic.

Question 29

What are the stages in genetic engineering?

Answer 29

1. Select the desired characteristic (e.g. insulin gene) 2. Isolate the gene responsible for the characteristic (using enzymes) 3. Insert this gene into another organism (e.g. a bacterium) 4. Replicate the organism.

Question 30

What are the advantages of genetic engineering?

Answer 30

1. Better crop yield 2. Extended shelf-life of fresh fruit/veg 3. Manufacture a certain chemical (e.g insulin)

Question 31

What are the disadvantages of genetic engineering?

Answer 31

1. Inserted genes may have unwanted side effects 2. Genetically modified crops may be harmful to humans/animals when eaten 3. Damages food chains 4.