2a) Cells, Organs and Populations

Question 0

What things do a plant cell contain that an animal/human cell doesn’t?

Answer 0

Rigid cellulose cell wall - supports the cell and strengthens it
Permanent vacuole - contains cell sap (weak solution of sugar + salts)
Chloroplasts - where photosynthesis occurs to make food, contain chlorophyll

Question 1

What does a human/animal cell have? (+plant cells)

Answer 1

Nucleus - contains genetic material that controls activities of the cell
Cytoplasm - where chemical reactions happen, has enzymes
Cell membrane - controls in and out
Mitochondria - where respiration
Ribosomes - proteins made

Question 2

What does a yeast cell contain?

Answer 2

Yeast = single celled organism
Nucleus - genetic material to control 
Cytoplasm - chemical reactions
Cell membrane - control in and out
Cell wall - support and strengthen

Question 3

What do Bacteria cells contain?

Answer 3

Bacteria = single celled organism
Cytoplasm - chemical reactions
Cell membrane - control in and out
Cell wall - support and strengthen

NO nucleus - genetic material floats in the cytoplasm

Question 4

What are all living things made of?

Answer 4

Cells

Question 5

What is the role of the nucleus in a cell?

Answer 5

Contains genetic material

Controls the activities of the cell

Question 6

What is the cytoplasm?

Answer 6

Gel-like substance
Where chemical reactions happen
Contains enzymes that control these chemical reactions

Question 7

What’s the importance if the cell membrane?

Answer 7

Hold the cell together

Controls what goes in and out

Question 8

Why do cells need mitochondria?

Answer 8

Where most of the reactions for respiration take place

Respiration releases energy that the cell needs to work

Question 9

What is the purpose of ribosomes in the cell?

Answer 9

Where proteins are made

Question 10

Why do plant cells have a rigid cell wall?

Answer 10

Supports and strengthens the cell

Made of cellulose

Question 11

What is cell sap and where is it found?

Answer 11

A weak solution of sugar and salts.

Inside vacuole in plant cells

Question 12

Why do plant cells have chloroplasts?

Answer 12

Contain a green substance called chlorophyll (to absorb sunlight)
Where photosynthesis occurs which makes food for the plant

Question 13

Define diffusion

Answer 13

Overall net movement or spreading out of particles from an area of high concentration to an area of low concentration

(Honey Lumps)

Question 14

Why does diffusion only happen in solutions and gases

Answer 14

Particles in these substances are free to move about randomly

Question 15

If the difference in concentration is big, what happens to the rate of diffusion?

Answer 15

The bigger difference in concentration, faster the diffusion rate

Question 16

Why can’t molecules like starch and proteins diffuse through cell membranes?

Answer 16

Big molecules - won’t fit through cell membrane

Question 17

Give some examples of molecules that can diffuse through cell membranes

Answer 17

Small molecules:

Oxygen, glucose, amino acids, water

Question 18

How are Palisade leaf cells adapted for photosynthesis?

Answer 18

Packed with chloroplasts - crammed at the top of the cell so closer to light
Tall shape - surface area exposed to absorb CO2 from air
Thin shape - packed at top of leaf where photosynthesis happens

Question 19

How are red blood cells adapted to carry oxygen?

Answer 19

Concave shape - big surface area to absorb oxygen, can pass smoothly through capillaries
Haemoglobin - red pigment that’s absorbs the oxygen
No nucleus - more room for haemoglobin

Question 20

How are sperm cells specialised for reproduction?

Answer 20

Long tail and streamlined head - help it swim to egg
Mitochondria - provide energy
Enzymes - digest through egg cell membrane

Question 21

How are guard cells adapted to allow gas exchange and control water loss within a leaf?

Answer 21

Kidney shape - to open and close the stomata
Turgid - stomata opens so gases can exchange for photosynthesis
Flaccid - stomata close go stop water vapour escaping
Thin outer walls, thick inner walls
Sensitive to light - close at night to save water

Question 22

How is an egg cell specialised for reproduction?

Answer 22

Food reserves to nourish embryo

Membrane instantly changes structure to stop more sperm entering - so offspring end up with right amount of DNA

Question 23

Define differentiation

Answer 23

The process by which cells become specialised for a particular job

Occurs during the development of a multicellular organism

Question 24

What are tissues?

Answer 24

Groups of similar cells that work together to carry out a particular function

Can include more than one type of cell
E.g. Muscular tissue

Question 25

What is an organ?

Answer 25

Group of different tissues that work together to perform a certain function

E.g. Stomach

Question 26

What is an organ system?

Answer 26

Groups of organs working together to perform a particular function

E.g. Digestive system

Question 27

What is the leaf made up of?

Answer 27

Mesophyll tissue - where photosynthesis occurs
Xylem and Phloem - transport
Epidermal tissue - covers plant

Question 28

What is the photosynthesis equation?

Answer 28

Carbon dioxide + water ~> glucose + oxygen (+energy)

Arrow stands for chlorophyll/sunlight

Question 29

What is photosynthesis?

Answer 29

The process of producing food (glucose) in plants and algae inside chloroplasts

Question 30

Where is chlorophyll found?

Answer 30

Chloroplasts in plant cells

Question 31

What is chlorophyll?

Answer 31

Green substance in chloroplasts
Absorb sunlight and uses energy to covert carbon dioxide (air) and water (soil) into glucose
Oxygen in produced as a by-product

Question 32

What is produced as a by-product of photosynthesis?

Answer 32

Oxygen (+energy)

Question 33

Why is sunlight needed for photosynthesis?

Answer 33

Provide energy for the process

Question 34

What is an organelle?

Answer 34

Parts of the cells which have a distinct structure and function

Question 35

What is the rate of photosynthesis affected by?

Answer 35

Limiting factors:

Intensity of light - provides energy
Volume of CO2 - raw material
Temperature - for enzymes

Question 36

What is a limiting factor?

Answer 36

Something that slows down the rate of photosynethesis

Question 37

How can you measure how fast photosynthesis is happening?

Answer 37

Measure amount of oxygen produced in a time period

Either count bubbles or collect oxygen in a gas syringe

Question 38

How can you change light intensity in a lab?

Answer 38

Move the lamp closer of further away from the plant

Question 39

Describe one way of increasing the amount of CO2

Answer 39

Dissolve some sodium hydrogen carbonate in the water which gives off CO2

Using a paraffin heater - CO2 created as a by-product

Question 40

Describe one way of controlling the temperature

Answer 40

Put the flask in a water bath

Question 41

At what temperature do enzymes usually get damaged?

Answer 41

45 degrees Celsius

Question 42

Name 5 ways plants use glucose

Answer 42

For respiration - provide energy
Making cell walls - glucose is converted into cellulose
Making proteins - combined with nitrate ions to make amino acids
Stored in seeds - turned into lipids
Stored as starch - energy store

Question 43

What environmental factor affect where an organism might live?

Answer 43

Temperature
Availability of water
Availability of oxygen and CO2
Availability of nutrients 
Amount of light

Question 44

How do you work out the mean number of organisms per quadrat?

Answer 44

Total organisms divided by number of quadrats

Question 45

How do you work out the population size of an area?

Answer 45

Mean no. Of organisms per m squared times by total area of habitat

Question 46

How can you measure the distribution of organisms?

Answer 46

Quadrats

Transect line