Paper 1- Topic 1

Question 1

Magnification triangle

Answer 1

Image size= actual size x magnification

Actual size =
Image size / magnification

Magnification =
Image size/ actual size

Question 2

What are stem cells

Answer 2

Undifferentiated cells which can specialise to form any type of cell

Question 3

What is therapeutic cloning

Answer 3

Producing an embryo with the same genes as the patient

Question 4

Why is therapeutic cloning used

Answer 4

To repair tissues or organs

Question 5

Advantages of human embryo stem cells

Answer 5

• good supply
• no operation involved
• can turn into any type of cell

Question 6

Disadvantages of human embryo stem cells

Answer 6

• can’t give consent
• new procedure so may not work
• potential life
• expensive

Question 7

Advantages of bone marrow stem cells

Answer 7

• consent can be given
• more ethical
• used to treat leukaemia

Question 8

Disadvantages of bone marrow stem cells

Answer 8

• operation has potential side effects

- limited supply

Question 9

How do particles move in DIFFUSION

Answer 9

High to low concentration

Question 10

Why is diffusion a passive process

Answer 10

No energy is required

Question 11

Factors that effect diffusion

Answer 11

• concentration
  (larger the conc. gradient the faster the rate of diff.)
• temperature
  (Increase in temp means more kinetic energy = increased rate of diff.)
• surface area of membrane
  ( increase SA = increases diff. as there is more space for diffusion to take place)

Question 12

How large surface area helps the exchange of substances

Answer 12

Shorter diffusion pathway for substances

Question 13

How thin membranes help the exchange of substances

Answer 13

Maintains a steep concentration gradient by removing diffusing substances

Question 14

How efficient blood supply helps the exchange of substances

Answer 14

Increases the rate of exchange

Question 15

3 stages of cell cycle

Answer 15

1) interphase
2) mitosis
3) cytokinesis

Question 16

eukaryotes

Answer 16

animal and plant cells

contain nucleus, cell membrane and cytoplasm

Question 17

prokaryotes

Answer 17

bacteria cells

do not contain nucleus

smaller than eukaryotes

contain plasmids. cell wall, cell membrane and cytoplasm

Question 18

nucleus

Answer 18

contains genetic material

in animal and plant cells

Question 19

cytoplasm

Answer 19

where chemical reactions take place

in animal and plant cells

Question 20

cell membrane

Answer 20

controls what goes in and out of cell

in animal and plant cells

Question 21

mitochondria

Answer 21

where aerobic respiration takes place

in animal and plant cells

Question 22

ribosomes

Answer 22

proteinsynthesis

in animal and plant cells

Question 23

chloroplasts

Answer 23

contain chlorophyll and are the sites of photosynthesis

in plant cells

Question 24

cell wall

Answer 24

strengthens cell

in plant cells

Question 25

vacuole

Answer 25

contains cell sap

in plant cells

Question 26

how sperm cell is specialised

Answer 26

long tail to help swim faster

mitochondria to give energy to swim

enzymes to help digest through ovum

Question 27

how nerve cell is specialised

Answer 27

long axon to help carry electrical impulses

covered in myelin to insulate the axon and speed up the transmission of nerve impulses

synapses to allow impulses to pass from one nerve cell to another

Question 28

how muscle cells are specialised

Answer 28

they can contract - contain protein fibres which change the length of the cell

full of mitochondria to provide energy to contract

Question 29

how root hair cells are specialised

Answer 29

hairs increase the surface area of the root to help absorb water and dissolve minerals

do not contain chloroplasts

Question 30

how xylem cells are specialised

Answer 30

form long tubes to carry water and minerals

thick walls containing lignin which provides support to the plant

have no internal structures to allow water to flow easier

Question 31

how phloem cells are specialised

Answer 31

phloem tubes carry dissolved sugars

sieve plates

Question 32

microscopes required practical

Answer 32

1) place slide on stage and select lowest power lens
2) make sure slide is in focus
3) use pencil to draw the cells

Question 33

light microscopes

Answer 33

limited magnification

limited resolution

less expensive

Question 34

electron microscopes

Answer 34

higher magnification

higher resolution

more expensive

Question 35

number of bacteria=

Answer 35

2^number of rounds of division

Question 36

culturing microorgansims method

Answer 36

1) sterilise bench with disinfectant
2) sterilise inoculating loop by passing through flame
3) open agar gel plate near bunsen burner
4) use loop to spread bacteria over plate getting less dense as you go
5) place filter paper discs containing antibiotics onto plate
6) incubate plate

Question 37

cell cycle

Answer 37

1) -dna replicates to form two copies of each chromosome
- cell grows and copies its internal structures

2) -mitosis takes place
- one set of chromosomes is pulled to each end of the cell
- nucleus divides

3) -cytoplasm and cell membrane divide to form two identical cells

Question 38

what is osmosis

Answer 38

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

Question 39

osmosis practical method

Answer 39

1) peel potato
2) use cork borer to crete potato cylinders
3) use scalpel to trim the cylinders to the same length
4) measure mass of each cylinder using scale
5) place each cylinder into test tube
6) add 10cm^3 of 0.5 molar sugar solution to first test tube
7) then repeat to second tube with a 0.25 molar solution
8) then repeat with third tube with distilled water
9) leave cylinders overnight
10) remove potato and roll on paper towel to remove surface moisture
11) measure length and mass again
12) calculate percentage change

Question 40

what is active transport

Answer 40

moves substances from a dilute solution to a more concentrated solution (against conc gradient)

requires energy from respiration