3 - Genetics

Question 1

What type of reproduction do humans use to produce offspring?

Answer 1

Sexual reproduction

Question 2

What is the male gamete in flowering plants?

Answer 2

B

Pollen is the male gamete in flowering plants

Question 3

A population of aphids are all clones of each other. Were they produced through sexual reproduction or asexual reproduction?

Answer 3

Asexual reproduction

Question 4

Eliza the lizard comes from a species which reproduces asexually. How are offspring produced using asexual reproduction?

Answer 4

In asexual reproduction, an ordinary cell makes a new cell by mitosis. This is where a cell divides into two, producing genetically identical offspring.

Question 5

Cats reproduce using sexual reproduction. What happens during sexual reproduction in cats?

Answer 5

A male and female cat each produce gametes by meiosis. These contain half the number of chromosomes of a normal cell. An egg from a female cat fuses with a sperm from a male cat, forming a cell with the full number of chromosomes

Question 6

Name the type of cell that are formed when a cell divides by meiosis. How many of these are formed each time a cell undergoes meiosis?

Answer 6

Gametes are formed by meiosis. There are four gametes produced each time a cell divides in this way.

Question 7

Where does meiosis take place in animals?

Answer 7

C. In animals, meiosis only occurs in the ovaries and the testes.

Question 8

How would the genetic material in one sperm cell compare to the genetic material in another sperm cell?

Answer 8

The genetic material will be different.

Question 9

A mouse body cell contains 40 chromosomes. How many chromosomes will be in the mouse cells produced by meiosis?

Answer 9

There will be 20 chromosomes in each cell (gamete) after meiosis.

Question 10

How does a fertilised egg divide to produce lots of cells in an embryo? What happens to these cells that allows them to form an organism?

Answer 10

A fertilised egg divides by mitosis. The cells in the embryo differentiate as the embryo develops

Question 11

Outline what happens during meiosis.

Answer 11

A cell duplicates its genetic information. The cell divides twice, resulting in the production of four gametes.

Question 12

True or false? DNA is contained in long structure called chromosomes

Answer 12

True

Question 13

What is bigger - a gene or a genome?

Answer 13

A genome is bigger than a gene

Question 14

How many strands make up a section of DNA? What shape do they form?

Answer 14

DNA is made up of two polymer strands. These two strands coil together into a double helix

Question 15

What is the importance of genes in the production of proteins?

Answer 15

Each gene codes for a specific sequence of amino acids which are put together to form a specific protein.

Question 16

How might studying the human genome be beneficial in medicine?

Answer 16

By studying a genome, scientists can identify genes that are linked to different diseases. Scientists can use this information to gain a better understanding of these diseases and to develop better treatments for them.

Question 17

Some scientists believe that all modern humans have descended from a common ancestor who lived in Africa. How could analysing the human genome help to trace the migration of humans since they first left Africa thousands of years ago?

Answer 17

The human genome is mostly identical in all individuals. Small differences arose when different populations began to migrate away from each other. By analysing these differences, we can work out when the new population split off and where they went.

Question 18

How many pairs of chromosomes are in a normal human body cell? How many of these pairs are involved in determining sex?

Answer 18

Normal human body cells contain 23 pairs of chromosomes. Only one of these pairs is involved in sex determination

Question 19

What chromosome(s) does each sperm cell contain?

Answer 19

Each sperm cell will contain either an X chromosome or a Y chromosome

Question 20

What is the probability of inheriting an X chromosome?

Answer 20

There is a 100% chance of inheriting an X chromosome because all eggs contain one X chromosome.

Question 21

Stephen and Greta have three sons and one daughter. Stephen thinks there is a 75% chance that their next child will be a boy. Explain whether or not Stephen is correct.

Answer 21

Stephen is not correct. The probability that the next child will have XX chromosomes is equal to the probability of the child having XY chromosomes. So there is a 50% chance of the child being a boy.

Question 22

How many genes are responsible for controlling whether a human is red-green colour blind?

Answer 22

1

Question 23

True or false? Characteristics are rarely caused by multiple genes interacting.

Answer 23

False

Some characteristics are caused by a single gene, but most characteristics are caused by multiple genes interacting.

Question 24

Is the variation in eye colour in humans due to the variation in genes or environment?

Answer 24

Variation in genes

Question 25

How do mutations introduce variants into populations?

Answer 25

Mutations change the sequence of bases in DNA, which produces a genetic variant

Question 26

When a mutation occurs, what is the most common outcome for the phenotype?

Answer 26

Most mutations have no effect on the phenotype

Question 27

Tom and Dom are identical twins. Tom weighs more than Dom. Dom has a scar on his back but Tom does not. What type of variation has caused these differences between Tom and Dom?

Answer 27

Environmental variation

Question 28

In a field of sunflowers, there is variation in plant height. Explain how this variation is caused.

Answer 28

Variation in the heights of the sunflowers is caused by a combination of genes and the environment. The maximum height of a sunflower is determined by the genes it has inherited, but whether it reaches that height is determined by environmental factors, such as how much sunlight it gets and the quality of the soil.