Cells

Question 1

Animal cells

Answer 1

Animal cells are eukaryotic, which means they have a nucleus and other structures which are surrounded by membranes

Question 2

Cytoplasm

Answer 2

A jelly-like material that contains dissolved nutrients, salts and structures called organelles. It is where many of the chemical reactions happen (in plant, animal and bacterial cells)

Question 3

Nucleus

Answer 3

A nucleus contains genetic material, including DNA, which controls the cell’s activities (in both plant and animal cells)

Question 4

Cell membrane

Answer 4

The cell membrane is permeable to some substances, but not to others, and so controls the movement of substances in and out of the cell (in plant, animal and bacterial cells)

Question 5

Mitochondria

Answer 5

Mitochondria are organelles that contain the enzymes for respiration, and where most energy is released in respiration (in both plant and animal cells)

Question 6

Ribosomes

Answer 6

Ribosomes are tiny structures where protein synthesis occurs (in both plant and animal cells)

Question 7

Plant cells

Answer 7

Plant cells are eukaryotic, which means they have a nucleus and other structures which are surrounded by membranes

Question 8

Chloroplast

Answer 8

An organelle that contains the green pigment - chlorophyll - which absorbs light energy for photosynthesis. It contains the enzymes needed for photosynthesis (only in plant cells)

Question 9

Cell wall

Answer 9

Plant and bacterial cell walls provide structure and protection. Only plant cell walls are made from cellulose (only in plant and bacterial cells)

Question 10

Permanent vacuole

Answer 10

Filled with cell sap to help keep the cell swollen (only in plant cells)
(Animal cells may also have vacuoles, but these are small and temporary)

Question 11

Bacterial cells

Answer 11

Bacteria are all single-celled. The cells are all prokaryotic. This means they do not have a nucleus or any other structures which are surrounded by membranes. They are amongst the simplest of organisms, and their cells do not divide during mitosis. Instead, they copy themselves by binary fission.

Question 12

Chromosomal DNA

Answer 12

The DNA of bacterial cells is found loose in the cytoplasm and is not contained within a nucleus

Question 13

Plasmid DNA

Answer 13

Bacteria have small, closed-circles of DNA called plasmids, present in their cytoplasm. Unlike chromosomal DNA, plasmid DNA can move from one bacterium to another giving variation

Question 14

Flagella

Answer 14

Bacteria can have one or more flagella (singular - flagellum). These can rotate or move in a whip-like motion to move bacterium

Question 15

Compare the sizes of eukaryotic and prokaryotic cells

Answer 15

Eukaryotic: 5 µm - 100 µm
Prokaryotic: 0.2 µm - 2.0 µm

Question 16

Compare the outer layers of eukaryotic and prokaryotic cells

Answer 16

Eukaryotic: Cell membrane. Surrounded by cell wall in plants and fungi
Prokaryotic: Cell membrane. Surrounded by cell wall

Question 17

Compare the cell contents of eukaryotic and prokaryotic cells

Answer 17

Eukaryotic: Cytoplasm. Cell organelles include mitochondria, chloroplasts in plants and ribosomes
Prokaryotic: Cytoplasm. Ribosomes present. There are no mitochondria or chloroplasts

Question 18

Compare the genetic material of eukaryotic and prokaryotic cells

Answer 18

Eukaryotic: DNA in a nucleus. Plasmids are found in a few simple eukaryotic organisms
Prokaryotic: DNA is a single molecule, found free in the cytoplasm. Additional DNA is found on one or more rings called plasmids

Question 19

Compare the types of cell division of eukaryotic and prokaryotic cells

Answer 19

Eukaryotic: Mitosis
Prokaryotic: Binary fission

Question 20

How is a sperm cell adapted to carry out its function?

Answer 20

Head - contains genetic material for fertilisation in a haploid nucleus
Acrosome (in the head) - contains enzymes so sperm can penetrate an egg
Middle piece - contains mitochondria to release energy needed to swim and fertilise egg
Tail - enables sperm to swim

Question 21

How is an egg cell adapted to carry out its function?

Answer 21

Cytoplasm - contains nutrients for the growth of the early embryo
Haploid nucleus - contains genetic material for fertilisation
Cell membrane - changes after fertilisation by a single sperm so that no more sperm can enter

Question 22

How is a ciliated epithelial cell adapted to carry out its function?

Answer 22

Cilia on the surface beat to move fluids and particles up the trachea

Question 23

How do you calculate the magnification of an object?

Answer 23

Magnification = size of image / real size of object

Question 24

Why do you stain cells before looking at them under a telescope?

Answer 24

Plant cells are usually stained with iodine stain to make the internal structures more visible. Most cells are colourless and stains can be used to add contrast.
However, cheek cells the stain methylene blue can be used to stain the nucleus blue

Question 25

1 µm = ? nm

Answer 25

1 000 nm

Question 26

1 m = ? cm

Answer 26

100 cm

Question 27

1m = ? mm

Answer 27

1 000 mm

Question 28

1m = ? µm

Answer 28

1 000 000 µm

Question 29

1m = ? nm

Answer 29

1 000 000 000 nm