B1

Question 1

What can a light microscope magnify up to?

Answer 1

-About X2000

Question 2

What can an electron microscope magnify up to?

Answer 2

-About X2000000

Question 3

What resolving power does a light microscope have?

Answer 3

-About 200nm

nm= nanometre

Question 4

What resolving power does an electron microscope have?

Answer 4

-About 0.2nm

nm= nanometre

Question 5

calculating the size of an object equation:

Answer 5

magnification = size of image/ size of real object
or
size of real object = size of image/ magnification

Question 6

what can an electron microscope be used for?

Answer 6

-viewing thin specimens (tissue sections, molecules)

Question 7

what can a light microscope be used for?

Answer 7

-viewing living cells (onion cells etc.)

Question 8

what are the cells features in an animal cell and what are their functions?

Answer 8

nucleus: controls the cell, contains genes (chromosomes)
cytoplasm: liquid gel where most chemical reactions occur
cell membrane: controls what enters and exits cell
mitochondria: where aerobic respiration takes place
ribosomes: makes proteins for cell and is where protein synthesis takes place

Question 9

what are the extra cells features in a plant cell and what are their functions?

Answer 9

cellulose, cell wall: strengthens the cells and gives it support

vacuole: filled with cell sap. keeps cell rigid to support plant
chloroplasts: contain chlorophyll which absorb light for photosynthesis

Question 10

what are the main structure you would expect to find in a human cell?

Answer 10

• nucleus
• cytoplasm
• cell membrane
• mitochondria
• ribosomes

Question 11

what extra features are found in plant cell but not animal cells?

Answer 11

• vacuole
• cell wall
• chloroplasts

Question 12

why are the nucleus and mitochondria so important?

Answer 12

• the mitochondria is where aerobic respiration takes place

- the nucleus controls the cell

Question 13

What do all eukaryotic cells have?

Answer 13

• cell membrane
• cytoplasm
• genetic material in a nucleus

Question 14

what do prokaryotes (bacterial cells) consist of?

Answer 14

• cytoplasm
• cell membrane
• cell wall
• genetic material not in a nucleus
• plasmids: extra small rings of dna
• slime capsule: extra protection
• flagella: to move
• ribosomes
• pili: hair-like structure allow bacterial cells to stick to other surfaces

Question 15

what can happen to an animal organism as it develops?

Answer 15

-cells can differentiate to form idfferent types of cells such as nerve cells, muscle cells, sperm cells etc.

Question 16

how are nerve cells adapted?

Answer 16

• lots of dendrites to make connections to other nerve cells
• axon carries nerve impulse for one place to another
• synapse (nerve ending) adapted to pass impulses to another cell

Question 17

how are muscle cells adapted?

Answer 17

• contain special proteins that slide over each other making fibres contract
• contain mitochondria to transfer energy needed for chemical reactions that occur as cells contract
• store glycogen that can be broken down and used for aerobic respiration

Question 18

how are sperm cells adapted?

Answer 18

• long tails whips to help move sperm
• middle section full of mitochondria which transfer energy needed for tail to work
• acrosome stores digestive enzymes for breaking down outer layers of the egg
• large nucleus contains genetic info to be passed on

Question 19

how are root hair cells adapted?

Answer 19

• increased surgace area for water to move into the cell
• vacuole speeds up movement of water by osmosis
• mitochondria transfer energy for active transport of mineral ions into root hair cells

Question 20

how are phloem cells adapted?

Answer 20

-cell walls break down to form sieve plates which allow water carrying dissolved food to move up + down tubes

Question 21

how are xylem cells adapted?

Answer 21

• cells die + form long hollow tubes to carry water + mineral ions from one end of plant to the other
• spirals and lignin help them withstand pressure of water moving up plant

Question 22

how are photosynthetic cells adapted?

Answer 22

• chloroplasts contain chlorophyll that trap light for photosynthesis
• continuous layers in leaves and outer layers of stem so they absorb most light
• vacuole helps keep leaf spread out to get most sunlight

Question 23

what is the function of root hair cells?

Answer 23

-to absorb minerals and water from soil

Question 24

what is the function of photosynthetic cells?

Answer 24

-plants can make their own food

Question 25

what is the function of xylem cells?

Answer 25

- to support the plant | - to carry water and mineral ions from roots to the highest leaves and shoots

Question 26

what is the function of phloem cells?

Answer 26

-carries food made by photosynthesis around the plant

Question 27

what is diffusion?

Answer 27

the spreading out of particles of any substance, in solution or gas, resulting in a net movement from a high concentration to an area of low concentration, down a concentration gradient

Question 28

why does diffusion take place faster when there is an increase in temperature?

Answer 28

-the particles in a gas or solution move around more quickly (speed up) so diffusion takes place more rapidly

Question 29

what affects the rate of diffusion?

Answer 29

- the difference in concentrations - the temperature - the available surface area

Question 30

what is a concentration gradient?

Answer 30

the difference between two areas of concentration

Question 31

define net movement:

Answer 31

net movement = particles moving in - particles moving out

Question 32

what is osmosis?

Answer 32

- a special type of diffusion - the movement of water from a dilute to a more concentrated solution through a partially permeable membranethat allows water to pass through

Question 33

what is the difference between osmosis and diffusion?

Answer 33

- osmosis occurs across a partially permiable membrane while diffusion does not - osmosis in organisms also only refers to the diffusion of water molecules

Question 34

what is a partially permeable membrane?

Answer 34

-membranes that only let some types of particles through

Question 35

in osmosis what is a dilute solution of sugar?

Answer 35

contains a high concentration of water and has a low concentration of sugar

Question 36

in osmosis what is a concentrated solution of sugar?

Answer 36

-contains a relatively low concentration of water and a high concentration of sugar

Question 37

what is an isotonic solution?

Answer 37

-when the concentration of solutes in the solution outside the cell is the same as the internal concentration

Question 38

what is a hypotonic solution?

Answer 38

-when the concentration of solutes in the solution outside the cell is lower than the internal concentration

Question 39

what is a hypertonic solution?

Answer 39

-when the concentration of solutes in the solution outside the cell is higher than the internal concentration

Question 40

what is a solute?

Answer 40

- the minor component in a solution | - dissolved in the solvent

Question 41

what is a solvent?

Answer 41

-the liquid in which a solute is dissolved to form a solution

Question 42

what do differences in the concentration of solutions inside and outside a cell do?

Answer 42

-cause water to move into or out of the cell by osmosis

Question 43

how can osmosis cause big problems in animals?

Answer 43

- if solution outside the cell becomes much more dilute than the cell contents water will move in by osmosis + the cell will swell + may burst - if solution outside the cell becomes much more concentrated than the cell contents, water will move out of the cell by osmosis + the cytoplasm will become to concentrated + the cell will shrivel up + die

Question 44

why is osmosis so important in plants cells?

Answer 44

- to maintain turger (hard and rigid) which keeps the leaves and stem of the plant firm - its the way the plants get water through its leaves and root hair cells

Question 45

how does active transport work in a cell?

Answer 45

-active transport moves substances from a more dilute solution to a more concentrated solution (against a concentration gradient)

Question 46

where does active transport get its energy for use from?

Answer 46

-active transport uses energy released from food in respiration to provide the energy required

Question 47

why is active transport important?

Answer 47

- it allows plant root hairs to absorb mineral ions required for healthy growth from very dilute solutions in soil against a concentration gradient - it enables sugar molecules used for cell respiration to be absorbed from lower concentrations in the gut into the blood where concentration of sugar is higher