B1

Question 1

What are eukaryotic cells

Answer 1

Eukaryotic cells have a cell membrane,
cytoplasm and genetic material (DNA)
enclosed in a nucleus.

Animal and plant cells are eukaryotic cells

Question 2

What are prokaryotic cells

Answer 2

These are smaller than eukaryotic
cells. The genetic material is not
enclosed in a nucleus. The DNA is a
single loop and there may be one or
more rings of DNA called plasmids.

Bacterial cells are prokaryotic cells

Question 3

Nucleus

Answer 3

Contains genetic material, which controls the
activities of the cell

Animal and Plant

Question 4

Cytoplasm

Answer 4

Most chemical processes take place here, controlled
by enzymes

Animal and Plant and Bacteria

Question 5

Cell membrane

Answer 5

Controls the movement of substances into and out of
the cell

Animal and Plant and Bacteria

Question 6

Mitochondria

Answer 6

Most energy is released by respiration here

Animal and Plant

Question 7

Ribosomes

Answer 7

Protein synthesis happens here

Animal and Plant

Question 8

Cell wall

Answer 8

Strengthens the cell – made of cellulose (not bacteria)
(algal cells also have a cell wall)

Plant and bacteria

Question 9

Chloroplasts

Answer 9

Contain chlorophyll, absorbs light energy for
photosynthesis

Plant only

Question 10

Permanent vacuole

Answer 10

Filled with cell sap to help keep the cell turgid

Plant only

Question 11

Bacterial DNA

Answer 11

Loop of DNA NOT found in a nucleus

Bacteria only

Question 12

Plasmid (DNA)

Answer 12

Small ring of DNA often used as a vector in genetic
modification

Bacteria only

Question 13

Sperm Cells

Answer 13

Function : To fertilise an egg

Characteristics : Streamlined with a long tail to swim the egg
Large number of mitochondria in the middle section release energy for movement

Question 14

Nerve Cells

Answer 14

Function : To carry electric signals

Characteristics : Long to carry signals long distances
Branched connections to send signals all over the body
Insulated sheath to enhance electric signals

Question 15

Muscle Cells

Answer 15

Contain a large number of mitochondria to
release energy from respiration for movement.

Long so that there is enough space to contract

Question 16

Root hair cells

Answer 16

Function : Absorb water and minerals from
the soil

Characteristics - Hair like projections to increase the surface area

Question 17

Xylem

Answer 17

Function : To carry water and minerals in plants

Characteristics - Form hollow xylem tubes made of dead tissue

Long cells with walls toughened by lignin

Water and minerals flow from the roots towards the
leaves only in one direction in a process called
transpiration

Question 18

Phloem

Answer 18

Function : Carry glucose around the plant

Characteristics - Form phloem tubes made of living tissue

Cells have end plates with holes in them

Glucose in solution moves from the leaves to growth and storage tissues in a process called translocation

Question 19

Cell differentiation

Answer 19

Cell differentiation occurs as organisms develop, the cell changes and becomes specialised. As the cell differentiates, it forms different sub-cellular structures, e.g. the tail on a sperm cell or the hairs on a root hair cell.

Question 20

Resolution

Answer 20

The shortest distance between two

objects that can be seen clearly

Question 21

Stages of the cell cycle

Answer 21

Stage 1 – Growth: Before a cell can divide it needs to grow and increase the
number of sub-cellular structures such as ribosomes and mitochondria.

Stage 2 - DNA synthesis: The DNA replicates to form two copies of each chromosome.

Stage 3 – Mitosis: One set of chromosomes is pulled to each end of the cell and the
nucleus divides. Then the cytoplasm and cell membranes divide to form two cells
that are identical to the parent cell.

Question 22

Stem Cells

Answer 22

Stem cells are undifferentiated cells within an organism. They can produce other stem cells that can then differentiate into many different types of cells

Question 23

Diffusion

Answer 23

The spreading of particles from a high to a low concentration

Question 24

Factors that affect diffusion

Answer 24

• The Concentration Gradient
• The Temperature
• The Surface Area of the Membrane

Question 25

Active Transport

Answer 25

Active transport moves substances and particles against the concentration gradient from a lower to a higher concentration

Question 26

Osmosis

Answer 26

Osmosis is the diffusion of water from a dilute solution to a concentrated solution through a partially permeable membrane.

Question 27

Adaptations of the Small Intestine

Answer 27

Internal surface is covered in millions of folds called villi. Villi increase the surface area. Villi have a very good blood supply. This maintains the concentration gradient. Membranes of the villi are very thin to allow for a short diffusion distance.

Question 28

Adaptations of the lungs

Answer 28

Lungs contain millions of tiny air sacs called alveoli. Alveoli increase the surface area. Alveoli have a very good blood supply. This maintains the concentration gradient. Membranes of the alveoli are very thin to allow for a short diffusion distance.

Question 29

Adaptations of fish gills

Answer 29

Each gill is made of lots of thin plates called gill filaments, water with low oxygen flows over them (however, the oxygen in the blood surrounding the gills is lower) . Gill filaments increase the surface area. Gill filaments are covered with lamella that increase the surface area more. Lamella have a very good blood supply. This maintains the concentration gradient as water flows in the opposite direction. Membranes of the lamellae are very thin to allow for a short diffusion distance.

Question 30

Adaptation of roots

Answer 30

The root surface is covered in millions of root hair cells. Root hair cells increase the surface area. Present on the mature parts of the roots. Absorb water and minerals from the soil.

Question 31

Adaptation of Leaves

Answer 31

Large surface area to absorb more light. Thin so short distance for carbon dioxide to diffuse into leaf cells. Chlorophyll absorbs sunlight for photosynthesis. Xylem and phloem to support the leaf and transport water and glucose. Stomata on the lower side of the leaf to allow gases to diffuse into and out of the leaf.