Topic 1 - Keys

Question 1

what are eukaryotes

Answer 1

cells with nuclei

Question 2

what are prokaryotes

Answer 2

cells without nuclei

Question 3

what is the function of the nucleus

Answer 3

contains genetic material, including DNA which controls the cell’s activities

Question 4

what is the function of the cytoplasm

Answer 4

jelly-like material containing dissolved nutrients + salts + structures (organelles). Many chemical reactions happen here

Question 5

what is the function of the cell membrane

Answer 5

it is permeable to some substances but not others so controls movement of substances in and out of cell.

Question 6

what is the function of the mitochondria

Answer 6

contains enzymes for respiration, and where most energy is released in respiration.

Question 7

what is the function of the ribosomes

Answer 7

where protein synthesis occurs

Question 8

what is the function of the chloroplasts

Answer 8

contains chlorophyll (a green pigment) which absorbs light energy for photosynthesis.

Question 9

what is the function of the vacuole

Answer 9

It has cell sap to keep cell turgid and swollen.

Question 10

what is the function of the cell wall

Answer 10

provides structure and protection. Made of cellulose in plants.

Question 11

what is the function of the chromosomal dna

Answer 11

it is DNA loose in the cytoplasm, not contained inside the nucleus.

Question 12

what is the function of the plasmid dna

Answer 12

small closed circles of DNA in cytoplasm, can move from one bacterium to another.

Question 13

what is the function of the flagella

Answer 13

tail to enable movement.

Question 14

what cell structures do animal cells contain

Answer 14

nucleus, cytoplasm, cell membrane, mitochondria, ribosomes

Question 15

what structures do plant cells contain

Answer 15

nucleus, cytoplasm, ribosome, vacuole, mitochondria, cell membrane, cell wall, chloroplast

Question 16

What are the adaptations of a sperm cell?

Answer 16

• It has acrosomes; contains enzymes so sperm can penetrate and digest the egg
• the head contains genetic material; for fertilisatoin in a haploid nucleus
• Lots of mitochondria; lots of energy release to swim
• The tail enables swimming and movement

Question 17

What are the adaptations of an egg cell?

Answer 17

• It has lots of cytoplasm which contains nutrients for growth of early embryo
• it has haploid nucleus containing genetic material for fertilisation
• the cell membrane changes after fertilisation so that only 1 sperm enters

Question 18

What are adaptations of ciliated epithilial cell?

Answer 18

It has cilia on surface beat to move fluids and particles up the trachea or into the stomach to be coughed up or destroyed (e.g. mucus)

Question 19

Resolution definition

Answer 19

shortest distance between 2 points on a speiment that can be seen as 2 different points by observer

Question 20

differences between light microsocope and electron microscope

Answer 20

LIGHT MICROSCOPE:
- light beam used
- see colour images
- smaller
- easier to use
- specimen can be alive
- lower resolving power
- lower magnificationm

ELECTRON MICROSCOPE:
- electron beam used
- black and white images
- specimen must be dead
- training required to use
- greater resolution
- greater magnification

Question 21

how to prepare onion slide for light microscope

Answer 21

1. use pipette to place drop of water in centre of slide
2. remove thin lyaer of onion with tweezers
3. place onion layer in water droplet
4. place iodine drop over onion slice with pipette
5. place cover slide over specimen
6. place slide onto microscope stage - ensure onion is at centre of stage

Question 22

how to work out magnification

Answer 22

Magnification = image size/actual size

Question 23

What is an enzyme?

Answer 23

A biological catalyst which speeds up rate of reaction but aren’t used up themselves

Question 24

Mechanism of enzymes

Answer 24

Enzymes are substrate-specific so active site of enzyme is complementary to substrate. When enzymes and substrates collide, an enzyme-substrate complex forms. After reaction, products leave the enzyme’s active site so it is free to collide with another substance.

Question 25

How to enzymes denature?

Answer 25

Bonds holding enzymes are disrupted due to high temperatures or extreme pHs. The active site shape is changed so enzymes can't bind with substrate. It is irreversible as the chain of amino acids unravel.

Question 26

What are factors affecting rate of enzyme activity?

Answer 26

1. Temperature - activity increased when temp up - molecules gain kinetic energy and move faster meaning more successful collisions - rate of reaction is increased. 2. Low temps - fastest rate occurs at optimum rate, if it is too low or too high it will cause denaturing - if the pH is too far from optimum, bonds will break. Optimum pH for most human enzymes is pH7, stomach acid is pH1. 3. Substrate concentration - if substrate concentration increases, activity increases. As concentration increases, likelihood increases of enzyme-substrate complexes being made increases. But the rate plateus at the saturation point - if enzyme concentration is fixed but substrate conc increases, all active sites become saturated; no more e-s complexes can form.

Question 27

What are digestive enzymes and products for digestive enzymes?

Answer 27

- CARBOHYDRATES broken down by AMYLASE producing GLUCOSE - LIPIDS broken down by LIPASE producing GLYCORD + 3 FATTY ACIDS - PROTEIN broken down by PROTEASE producing AMINO ACIDS

Question 28

Where is protease found

Answer 28

in the small intestine and stomach.

Question 29

What is diffusion?

Answer 29

Passive transport of substances from high to low concentrations. It occurs in liquids and gases as particles move randomly.

Question 30

What are the factors affecting rate of diffusion?

Answer 30

1. Temperature 2. Concentration gradient 3. Diffusion distance 4. Surface area

Question 31

How does temperature affect diffusion

Answer 31

Increase in temp means faster diffusion More kinetic energy of particles = more collisions

Question 32

How does concentration gradient affect diffusion

Answer 32

Greater the difference in concentration = increase in rate

Question 33

How does diffusion distance affect diffusion

Answer 33

The shorter distance = increase in rate because particles have less to travel through

Question 34

How does surface area affect diffusion

Answer 34

larger SA = increase in rate because more space for particles to moce through

Question 35

What is osmosis?

Answer 35

passive transport of water from area of high water concentration to low concentration across a semi permeable membrane to reach state of equilibrium

Question 36

What is hypertonic solution

Answer 36

Environment outside cell has high solute concentration than inside. Water moves out of the cell. Cell becomes plazmolyzed.

Question 37

What is hypotonic solution?

Answer 37

Environment outside has lower solute concetnration than inside. Water moves into the cell. Cell swells become turgid.

Question 38

What is isotonic solution?

Answer 38

Environment outside and inside cell have equal solute concetration. No net movement of water molecules. Cell stays the same - flaccid.

Question 39

What is active transport?

Answer 39

Transport used to move molecules from low to high concentration - against the concentration gradient. Requires ATP energy.

Question 40

How does calorimetry work?

Answer 40

1. Take tube of cold water 2. Record starting temperature of water 3. Hold burning food sample beneath test tiube 4. Record final temp of water when food burnt up 5. Work out the energy transfered to water by using: energy transfered = mass of water x temp increase x 4.2

Question 41

What is test for starch

Answer 41

Iodine solution Iodine goes from orange to blue/black

Question 42

What is test for sugars

Answer 42

Benedict's solution Blue to red/brown

Question 43

What is test for protein

Answer 43

Biuret's test (potassium hydroxide + copper sulfate) Blue to violet

Question 44

What is test for lipids

Answer 44

Emulsion test (ethanol) White emulsion layer formed at top of sample