Key Concepts in Biology

Question 1

Active site

Answer 1

A specific region on an enzyme where the substrate binds and the reaction takes place.

Question 2

Active transport

Answer 2

The movement of substances from a low concentration to a higher
concentration (against the concentration gradient) across a membrane, with the use of
energy from respiration.

Question 3

Cell membrane

Answer 3

A partially permeable barrier that surrounds the cell.

Question 4

Cell wall

Answer 4

An outer layer made of cellulose that strengthens plant cells

Question 5

Chloroplast

Answer 5

An organelle that is the site of photosynthesis.

Question 6

Cilia

Answer 6

Hair-like structures found on ciliated epithelial cells which waft substances across the
surface of the tissue in one direction.

Question 7

Concentration gradient

Answer 7

The difference in concentration between two areas.

Question 8

Denatured

Answer 8

Upon exposure to high temperatures or extremes of pH, the permanent
change in the shape of an enzyme’s active site that prevents the binding of a substrate.

Question 9

Diffusion

Answer 9

The net spreading out of particles from a high concentration to a lower
concentration (down their concentration gradient)

Question 10

Diploid cell

Answer 10

A cell that contains two copies of each chromosome (i.e. a full set of
chromosomes).

Question 11

Egg cell

Answer 11

A specialised female sex cell involved in reproduction.

Question 12

Electron microscope

Answer 12

• A type of microscope that uses a beam of electrons, focused using
  magnets, to produce an image of a specimen. It has a greater magnification and resolution
  than a light microscope.

Question 13

Enzyme

Answer 13

A biological catalyst that increases the rate of reactions in living organisms.

Question 14

Eukaryotic cell

Answer 14

A type of cell found in plants and animals that contains a nucleus.

Question 15

Flagella

Answer 15

A long hair-like structure found on bacterial cells that is used for cell movement.

Question 16

Haploid cell

Answer 16

A cell that contains a single copy of each chromosome (i.e. half the number of
chromosomes).

Question 17

Lipid

Answer 17

A large molecule that is synthesised from fatty acids and glycerol

Question 18

Magnification

Answer 18

magnification = image size / object size

Question 19

Mitochondria

Answer 19

An organelle that is the site of respiration.

Question 20

Nucleus

Answer 20

An organelle found in most eukaryotic cells that contains the genetic material of
the cell and controls the activities of the cell.

Question 21

Osmosis

Answer 21

The diffusion of water molecules from a region of high water concentration to a
region of lower water concentration across a partially permeable membrane.

Question 22

Plasmid

Answer 22

Loops of DNA found in the cytoplasm of prokaryotic cells.

Question 23

Prokaryotic cell

Answer 23

A type of cell found in bacteria that does not contain a nucleus.

Question 24

Protein

Answer 24

A large molecule that is synthesised from amino acids.

Question 25

Resolution

Answer 25

The smallest distance between two objects that can be distinguished.

Question 26

Ribosomes

Answer 26

Sub-cellular structures that are the site of protein synthesis.

Question 27

Sperm cell

Answer 27

A specialised male sex cell that is involved in reproduction

Question 28

Vacuole

Answer 28

An organelle found in plant cells which stores cell sap and supports the cell.