Unit 2.4: Variation & Inheritance

Question 1

Describe how sexual reproduction contibutes to variation within a species.

Answer 1

Sexual reproduction creates variation in a species by combining genetic information

Question 2

Define polygenic inheritance.

Answer 2

Features which are controlled by many genes

Question 3

What type of variation is shown in characteristics controlled by polygenic inheritance?

Answer 3

Continuous variation

Question 4

What is a gene?

Answer 4

A section of DNA

Question 5

What is an allele?

Answer 5

Different forms of the same gene

Question 6

What is a phenotype?

Answer 6

The colour an organism shows

Question 7

Describe a dominant allele

Answer 7

The allele that shows up in the phenotype maskinb the ressecive

Question 8

Describe a recessive allele?

Answer 8

The allele that doesn’t show in the phenotype as it is masked but still present in the genotype

Question 9

What is the term used to describe two alleles which are the same?

Answer 9

Homozygous

Question 10

What is the term used to describe two alleles which are different?

Answer 10

Heterozygous

Question 11

What is the function of the upper epidermis?

Answer 11

The protected layer that lets light through

Question 12

What is the function of the palisade mesophyll?

Answer 12

Photosynthesis

Question 13

What is the function of the spongy mesophyll?

Answer 13

Photosynthesis

Question 14

What is the function of the vein?

Answer 14

To allow water to be transported to be a leaf

Question 15

What is the function of the guard cells?

Answer 15

To control the opening and closing of stomata

Question 16

What is the function of the stomata?

Answer 16

Tiny holes which water and oxygen leave and carbon dioxide enetrs the leaf

Question 17

What vessels are found in veins?

Answer 17

xylem and phloem vessel

Question 18

What part of the plant is involved in water transport?

Answer 18

roots, stem and leaves

Question 19

Describe how the root is specialised for its role of water absorption.

Answer 19

Roots have root hairs which increase the surface area

Question 20

Name the vessel responsible for water transport.

Answer 20

xylem

Question 21

Describe the structure of xylem vessels.

Answer 21

Dead hollow tube

contains ligin

Question 22

Why are xylem cells lignified?

Answer 22

To withstand pressure change as water moves through the plant

Question 23

State the name of the vessels responsible for sugar transport.

Answer 23

phloem

Question 24

Describe the structure of phloem vessels.

Answer 24

Alive
sieve plates  (not done)

Question 25

What is transportation?

Answer 25

The process of water moving through a plant and is evaportated through the stomata

Question 26

Explain how root cells transport water.

Answer 26

It takes water from the soil by osmosis

Question 27

Explain how xylem transport water.

Answer 27

The cohesive forces link the water molecules together and pull them up the xylem vessels

Question 28

Explain how stomata transport water.

Answer 28

water evaporates

Question 29

Name the external factors that affect the rate of transpiration.

Answer 29

Temperature
Humidity
Wind speed

Question 30

Describe the best conditions for maximising the rate of transpiration.

Answer 30

Large surface area
High temperature
High wind speed
Low humidity

Question 31

Name the apparatus used to measure transpiration.

Answer 31

Potometer

Question 32

How is the rate of transpiration calculated?

Answer 32

Water loss/time