Cell Biology

Question 1

What are the two types of cells?

Answer 1

● Eukaryotic (plant and animal)

● Prokaryotic (bacteria)

Question 2

What are the differences between

eukaryotic and prokaryotic cells?

Answer 2

Prokaryotic cells are much smaller than
eukaryotic cells.
Eukaryotic cells contain membrane
bound-organelles and a nucleus containing
genetic material, while prokaryotes do not.

Question 3

What is the prokaryotic cell wall

composed of?

Answer 3

Peptidoglycan

Question 4

How is genetic information stored in a

prokaryotic cell?

Answer 4

Found free within the cytoplasm as:
● Chromosomal DNA (single large loop of circular DNA)
● Plasmid DNA

Question 5

List the components of both plant and
animal cells (5)

Answer 5

● Nucleus
● Cytoplasm
● Cell membrane
● Mitochondria
● Ribosomes

Question 6

List the additional cell components found

in plant cells (3)

Answer 6

● Chloroplasts
● Permanent vacuole
● Cell wall

Question 7

Other than storing genetic information,

what is the function of the nucleus?

Answer 7

Controls cellular activities

Question 8

What is the function of the cytoplasm?

Answer 8

Site of cellular reactions e.g. first stage
of respiration.
Transport medium.

Question 9

What is the function of the cell

membrane?

Answer 9

Controls the entry and exit of materials

into and out of the cell.

Question 10

What is the function of the mitochondria?

Answer 10

Site of later stages of aerobic respiration

in which ATP is produced.

Question 11

What is the function of the ribosomes?

Answer 11

Joins amino acids in a specific order
during translation for the synthesis of
proteins.

Question 12

What is the plant cell wall made of?

Answer 12

Cellulose

Question 13

What is the function of the plant cell

wall?

Answer 13

● Provides strength.
● Prevents the cell bursting when water
enters by osmosis.

Question 14

What does the permanent vacuole

contain?

Answer 14

Cell sap (a solution of salts, sugars and
organic acids).

Question 15

What is the function of chloroplasts?

Answer 15

Site of photosynthesis

Question 16

Describe how sperm cells in animals are

adapted to their function

Answer 16

● Haploid nucleus contains genetic information.
● Tail enables movement.
● Mitochondria provide energy for tail movement.
● Acrosome contains enzymes that digest the egg cell
membrane.

Question 17

Describe how nerve cells in animals are

adapted to their function

Answer 17

● Long axon allows electrical impulses to be transmitted all over
the body from the central nervous system.
● Dendrites from the cell body connect to and receive impulses
from other nerve cells, muscles and glands.
● Myelin sheath insulates the axon and speeds up the
transmission of impulses along the nerve cell.

Question 18

Describe how root hair cells in plants are

adapted to their function

Answer 18

● Large surface area to absorb nutrients and
water from surrounding soil.
● Thin walls that do not restrict water
absorption.

Question 19

Describe how phloem cells in plants are

adapted to their function

Answer 19

● Sieve plates let dissolved amino acids and
sugars be transported up and down the stem.
● Companion cells provide energy needed for
active transport of substances along the
phloem.

Question 20

Describe how xylem cells in plants are

adapted to their function

Answer 20

● No upper or lower margins between cells
to provide a continuous route for water to flow.
● Thick, woody side walls strengthen their
structure and prevent collapse.

Question 21

What is cell differentiation?

Answer 21

The process by which cells become

specialised.

Question 22

For how long do plant cells retain the

ability to differentiate?

Answer 22

Throughout their entire life cycle

Question 23

How can magnification be calculated?

Answer 23

magnification =

size of image / size of real object

Question 24

How do bacteria multiply?

Answer 24

Binary fission

Question 25

Why are cultures incubated at 25oC in | school laboratories?

Answer 25

Harmful pathogens are less likely to to | grow at this temperature.

Question 26

What are chromosomes made up of?

Answer 26

Chromosomes consist of DNA molecules combined with proteins. They contain genes which provide the instructions for protein synthesis.

Question 27

What is a gene?

Answer 27

A section of DNA which codes for a | protein.

Question 28

How many chromosomes are found in | the nucleus of human body cells?

Answer 28

46

Question 29

How many chromosomes are found in the | nucleus of gametes?

Answer 29

23

Question 30

What are the stages of cell division?

Answer 30

Prophase, metaphase, anaphase, telophase

Question 31

Describe the first stage of the cell cycle

Answer 31

Longest stage - cells grow and increase in mass, replicate DNA and synthesise more organelles (eg. mitochondria, ribosomes).

Question 32

What is a stem cell?

Answer 32

An unspecialised cell which is capable of differentiating into other cell types and of self-renewal.

Question 33

What is the function of stem cells in embryos?

Answer 33

Embryonic stem cells can replicate themselves and differentiate into many other types of cells. Embryonic stem cells may be able to treat conditions such as paralysis and diabetes by dividing to replace damaged cells.

Question 34

What is the function of stem cells in adult bone | marrow?

Answer 34

Adult stem cells can differentiate into several cell types to replace dead or damaged tissues. For example, bone marrow stem cells can form many different types of blood cell.

Question 35

What is therapeutic cloning?

Answer 35

A cloning method where an embryo is produced with the same genetic makeup as the patient. The stem cells which originate from the embryo will not be rejected by the patient’s immune system, so can be used to treat certain medical conditions.

Question 36

What are issues are associated with the use | of embryonic stem cells?

Answer 36

● Many embryonic stem cells are sourced from aborted embryos - some people have an ethical/religious objection. ● Development of stem cell therapies is slow, expensive and difficult. ● Adult stem cells infected with viruses could transfer infections to patients. ● If donor stem cells do not have a similar genetic makeup to the patient, an immune response could be triggered.

Question 37

What is diffusion?

Answer 37

The net movement of particles from an area of higher concentration to an area of lower concentration.

Question 38

What three main factors affect the rate of | diffusion?

Answer 38

● Concentration gradient - larger gradient, faster diffusion. ● Temperature - higher temperature, faster diffusion. ● Surface area - larger surface area, faster diffusion.

Question 39

Give examples of substances transported by | diffusion in the lungs and the kidney

Answer 39

● Lungs: oxygen diffuses into the blood from the lungs and carbon dioxide diffuses into the lungs from the blood, both down their concentration gradient. ● Kidney: urea diffuses from cells into blood plasma so it can be excreted in urine.

Question 40

How are single-celled organisms adapted for | diffusion?

Answer 40

They have a large surface area to volume ratio - maximises the rate of diffusion of molecules to meet the organism’s needs.

Question 41

What is osmosis?

Answer 41

The movement of water from a dilute solution to a concentrated solution through a partially permeable membrane.

Question 42

What is meant when a solution is isotonic to a | cell?

Answer 42

The concentrations of the external and | internal (inside cell) solutions are the same.

Question 43

What is meant when a solution is hypertonic to a | cell?

Answer 43

The concentration of the external solution is higher than that of the internal solution (inside cell).

Question 44

What is meant when a solution is | hypotonic to a cell?

Answer 44

The concentration of the external solution is lower than that of internal solution (inside cell).

Question 45

What may happen when an animal cell is placed | in a hypotonic solution?

Answer 45

Water moves into the cell, causing it to burst.

Question 46

What may happen when an animal cell is placed | in a very hypertonic solution?

Answer 46

Water moves out of the cell, causing it to shrivel | up.

Question 47

What is active transport?

Answer 47

The movement of molecules from a more dilute solution to a more concentrated solution against a concentration gradient, using energy from respiration.

Question 48

How do plant root hair cells use active transport?

Answer 48

Root hair cells use active transport to take up mineral ions from a more dilute solution in soils. Ions such as magnesium and nitrates are required for healthy growth.

Question 49

How is active transport used to absorb the | products of digestion?

Answer 49

Active transport is used to transport glucose from a lower concentration in the gut to a higher concentration in the blood. Glucose is then transported to the tissues where it can be used in respiration.