Unit 1

Question 1

Prokaryotic

Answer 1

Smaller, simpler cells e.g. bacteria

Question 2

Eukaryotic

Answer 2

More complex e.g. plant and animal cells

Question 3

Animal sub-cellular structures

Answer 3

Nucleus 
Cytoplasm
Membrane
Ribosomes
Mitochondria

Question 4

Plant sub-cellular structures

Answer 4

Nucleus
Cytoplasm
Membrane
Mitochondria 
Ribosomes
Cell wall
Chloroplasts
Vacuole

Question 5

Nucleus

Answer 5

Contains genetic material that control the activity of the cell

Question 6

Cytoplasm

Answer 6

A gel-like substance where most of the activities of the cell takes place

Question 7

Mitochondria

Answer 7

Where most of the respiration reactions take place. Respiration transfers energy that the cell needs to work

Question 8

Membrane

Answer 8

Holds the cell together and controls what goes in and out

Question 9

Ribosomes

Answer 9

Ribosomes are involved in the translation of genetic material in the synthesis of proteins

Question 10

Cell wall

Answer 10

Supports and strengthens the cell

Question 11

Vacuole

Answer 11

It maintains the internal pressure to support the cell.

Question 12

Chloroplasts

Answer 12

Where photosynthesis occurs

Question 13

Chromosomal DNA

Answer 13

A long circular chromosome that controls the cell’s activities and replication

Question 14

Plasmid DNA

Answer 14

Small loops of extra DNA that aren’t part of the chromosome. Plasmid DNA contains genes for drug resistance which can be passed between bacteria

Question 15

Flagellum

Answer 15

A long, hair-like structure that rotates to move the bacterium. It can be used to make the bacteria swim away from harmful substances and move towards beneficial things like nutrients

Question 16

Specialised cells

Answer 16

Specialised cells have a structure that makes them well adapted to their function.

Question 17

Egg cell

Answer 17

Function: carry the female DNA

• contains nutrients in the cytoplasm to feed the embryo
• haploid nucleus
• Straight after fertilisation it’s Membrane changes shape to stop anymore sperm getting in. This makes the offspring end up with the correct number of DNA

Question 18

Sperm cell

Answer 18

Function: transports the male DNA to the female’s egg.

• long tail so it can swim fast to the egg
• lots of mitochondria to provide energy from respiration to allow sperm swim
• haploid nucleus
• acrosome at the front of the head, where it stores enzymes needed to digest through the membrane of the egg cell

Question 19

Ciliated epithelial cells

Answer 19

Epithelial cells line the surface of organs. Cilia is a hair-like substance on top of the surface of the cell.
Ciliated epithelial cells move substances- the cilia beat to move substances in one direction along the surface of the tissue.
For example, the lining of the airways contains lots of ciliated epithelial cells so it can move mucus up the throat and into the mouth where it can be swallowed and won’t reach the lungs.

Question 20

Microscopes history

Answer 20

Light microscopes where invented in the 1590s. They work by passing light through a specimen to allow us to see things like nuclei and chloroplasts
Electron microscopes were invented in the 1930s and use electrons rather than light. They have a higher magnification and resolution to allow us to see smaller things in more detail like the internal structure of su-cellular structures. This gives us a better understanding on how cells work.

Question 21

Magnification equations

Answer 21

Total magnification= eye piece lens magnification X objective lens magnification

OR

Magnification = image size/ actual size

Question 22

Enzymes

Answer 22

Enzymes are biological catalysts. A catalyst is a substance which increases the speed of a reaction, without being changed or used up.

Question 23

How do enzymes speed up reactions?

Answer 23

Every enzyme has an active site. This is where it joins onto a substrate to catalyse a reaction.
For the enzyme to work, the substrate has to fit into the active site. If the substrate doesn’t fit the enzyme’s active site the reaction can’t be catalysed.

Question 24

Affect of temperature on enzymes

Answer 24

Changing the temperature changes the rate of an enzyme-catalysed reaction.
Increasing the temperature at first buy i gets too hot so some bonds holding the enzyme together break which changes the shape of the active site.

Question 25

Affect of PH on enzymes

Answer 25

Ph affects enzymes. If it gets too high or too low, PH interferes with the bonds holding the enzyme together. This denatures the enzyme.

Most enzymes have an optimum PH of 7

Question 26

Affect of substrate concentration on enzymes

Answer 26

The higher the substrate concentration, the faster the reaction as it is more likely the enzyme will meet up and react with a substrate. Up to a point, the active sites are full so adding more will make no difference

Question 27

Ph and enzyme investigation controls

Answer 27

1. The same volume of substrate and enzyme. (Different volumes can change the rate of reaction).
2. Same concentration of enzyme and substrate.(same reason)
3. Same temperature

Question 28

Rate calculation

Answer 28

Rate = 1000/time

Rate in cm3s-1

Question 29

Carbohydrases

Answer 29

Carbohydrases convert carbohydrates into simple sugars

Question 30

Proteases

Answer 30

Proteases convert proteins into amino acids

Question 31

Lipases

Answer 31

Lipases convert lipids into fatty acids and glycerol

Question 32

Diffusion

Answer 32

Diffusion is the gradual movement of particles from an area of higher concentration to an area of lower concentration

Question 33

Osmosis

Answer 33

Osmosis is the net movement of water molecules across a partially permeable membrane from a region of higher water concentration to an area of lower water concentration

Question 34

Heterotroph

Answer 34

Find own food

Question 35

Autotroph

Answer 35

Make their own food

Question 36

Saprotroph

Answer 36

Feed off dead matter