B1

Question 1

Features of a eukaryotic cell:

Answer 1

Larger than prokaryotic cells
Contains a cell membrane DNA contained in a nucleus
Plants and fungi, cell wall

Question 2

Features of a prokaryotic cell

Answer 2

Smaller than eukaryotic cells. Cell wall and membrane
Do not have chloroplasts or mitochondria
DNA is a single molecule found free in the cytoplasm
Additional DNA is found on plasmids

Question 3

Features of the xylem

Answer 3

Form long hollow tubes, role is to carry water. This is useful as the xylem is carrying water around the plant

Question 4

Features of the palisade

Answer 4

Large surface area for photosynthesis many chloroplasts, helps them because they absorb as much sunlight as possible

Question 5

Features of the nerve cell

Answer 5

Very thin and long, branched connections, this helps because they can carry joined messages up and down the body over large distances

Question 6

Features of the red blood cell

Answer 6

Contains haemoglobin flat disc biconcave shape large surface area how this helps is because it carries oxygen molecules

Question 7

Features of muscle cell

Answer 7

Held together in bundles, how it helps is that it pulls together to make muscles contract

Question 8

Light microscopes and electron microscopes

What is the difference?

Light microscopes

Answer 8

Beam of light (longer wavelength)
Small
Relatively inexpensive (cheap)
Not a lot of training required
See colour images
Specimen can be alive and unharmed
Lower resolving power
Lower magnification

Question 9

Electron microscopes

How are they different compare to light microscopes?

Answer 9

Beam of electrons (shorter wavelength)
Large and non portable
Expensive
Training required
Black and white images
Specimen must be dead
Greater resolution
Greater magnification

Question 10

How to prepare a slide and view using a microscope

Answer 10

Place the specimen on a slide. If necessary, add stain. Select the objective lens with the lowest magnification. Look through the eyepiece and turn the focus wheel slowly until you see your object. Repeat with objective lenses of a higher magnification to see the object in greater detail. (Add iodine solution to specimen)

Question 11

Formulae for actual size

Answer 11

Actual size = image size
—————
Magnification

Question 12

Formulae for image size

Answer 12

Actual size x magnification

Question 13

Main purpose of cell division in mature animals

Answer 13

Cells divide to replace old or damaged cells. Cell division helps in replacing tissues after injuries or wounds

Question 14

What is cell differentiation?

Answer 14

Process of cells becoming specialised as their body develops

Question 15

WHERE are chromosomes found in a human body cell?

Answer 15

Nucleus

Question 16

What is the importance of cell differentiation?

Answer 16

Cell differentiation is essential for developing specialised cells forming tissues and organs, maintaining and repairing the body, enabling adaptation and advancing regenerative medicine.

Question 17

What is a stem cell?

Answer 17

Unspecialised cell