B4

Question 1

What is the formula for the capture-recapture method?

Answer 1

Pop size = Total in 1st sample X total in 2nd sample / no. in 2nd sample previously marked

Question 2

What is zonation?

Answer 2

Where changes in abiotic factors influence the areas in which organisms live

Question 3

What is the equasion for photosynthesis?

Answer 3

6CO2 + 6H2O —> C6H12O6 + O2

Question 4

What two scientists looked at photosynthesis and what experiments did they do?

Answer 4

Helmont: Growth not just from soil nutrients
Priestley: Mouse experiments

Question 5

How did scientists discover the oxygen produced in photosynthesis came from carbon dioxide and water?

Answer 5

They used radioactive oxygen-18, radioactive oxygen is only created when the radiation comes from the water. They found it was a two stage process: Light energy splits water into oxygen and hydrogen ions, then the carbon dioxide combines with the hydrogen ions so glucose and oxygen are formed

Question 6

Name the layers of a leaf

Answer 6

Waxy cuticle, upper epidermis, palisade layer, spongy mesophyll & vascular bundles, lower epidermis, stomata & guard cells

Question 7

Why are plants green?

Answer 7

The pigments in chlorophyll mainly absorb purple and red light, so they reflect the opposite - green

Question 8

What is diffusion?

Answer 8

Net movement of particles from a high to low concentration

Question 9

How can you increase the rate of diffusion?

Answer 9

• Smaller distance for particles to travel
• Greater concentration gradient
• Greater surface area of cell membrane

Question 10

What is osmosis?

Answer 10

Diffusion of water from high to low concentration of water through a partially permeable membrane

Question 11

Why can animal cells swell or shrivel up?

Answer 11

Because water moves in and out through osmosis, but they don’t have an inelastic cell wall to control water content

Question 12

What are the names for when a blood cell burst and when it shrivels?

Answer 12

Swells (bursts) - Lysis

Shrivels - Crenated

Question 13

How do young, non-woody plants stay upright?

Answer 13

By having having turgor pressure (water pushing up against the cell wall), if there isn’t enough water the plant becomes flaccid

Question 14

What happens when plant cells lose lots of water?

Answer 14

Plasmolysis - the inside contracts

Question 15

What is a xylem and what do they do?

Answer 15

A vascular bundle in plants which transports water and soluble minerals from roots to leaves. Made from dead plant cells and have a hollow lumen.

Question 16

What is a phloem and what do they do?

Answer 16

A vascular bundle - transports sugars (food) up and down the stem to tissues.

Question 17

What is transpiration?

Answer 17

The diffusion and evaporation of water from inside a leaf. Water evaporates, water passes by osmosis from xylem vessels into leaf, thread of water inside xylem is pulled up so water enter xylem through root tissues to replace it, and more water enters the root hair cells.

Question 18

What factors affect transpiration?

Answer 18

Light, air movement (wind), temperature, humidity

Question 19

How can you measure transpiration?

Answer 19

Put water and roots in a sealed bag then measure mass before and after.

Question 20

How are plants adapted to not loose too much water?

Answer 20

Position, size and distribution of stomata vary on every plant depending on environment, turgidity of guard cells changes in relation to light intensity and water availability.

Question 21

When do guard cells open and close?

Answer 21

During photosynthesis they are turgid (open), if there is a lack of water they become flaccid (closed) and prevent water loss

Question 22

What happens to a plant if there is a lack of nitrates?

Answer 22

Poor growth, yellow leaves. Nitrates are used to make amino acids to form proteins for growth

Question 23

What happens to a plant if there is a lack of potassium?

Answer 23

Poor flower, dark leaves. Helps enzymes in photosynthesis and respiration.

Question 24

What happens to a plant if there is a lack of phosphates?

Answer 24

Poor root growth, spotty/discoloured leaves. Make DNA and cell membranes.

Question 25

What happens to a plant if there is a lack of magnesium?

Answer 25

Yellow leaves. Makes chlorophyll for photosynthesis.

Question 26

What is active transport and what is it used for?

Answer 26

When a plant needs to absorb something from a low to high concentration (against the gradient). It requires energy from respiration. It’s how plants absorb mineral ions through root hairs.

Question 27

How can you speed up decay?

Answer 27

Changing temperature (microorganisms work best at 40°C), more oxygen increases respiration, moister conditions for growth

Question 28

What are detrivores?

Answer 28

Earthworms, maggots and woodlice.

Break substances down to have large surface area so it is easier for microorganisms to break it down (speeds up decay)

Question 29

What are fungi/how do they work?

Answer 29

They are saphrophytes- they secrete enzymes onto material then absorb the digested products.

Question 30

How can you preserve food?

Answer 30

Pickling (acid kills microorganisms), sealing to prevent entry, preserve in sugar/ salt removes all water by osmosis, dried reduces moisture, kept at low temps to slow down growth.

Question 31

What are some examples of intensive farming?

Answer 31

Hydrophonics, fish farms, battery farming, glasshouses

Question 32

What is an advantage and disadvantage of organic farming?

Answer 32

Advantages: food and environment aren’t contaminated, biodiversity is encouraged and it’s more fair to animals
Disadvantages: expensive, more space needed, less efficient

Question 33

What is an advantage and disadvantage of hydrophonics?

Answer 33

Advantages: less risk of disease, minerals easily adjusted
Disadvantages: Support needed, expensive fertilisers needed

Question 34

What is an advantage and disadvantage of biological control?

Answer 34

Advantages: no repeat of treatment, pests can’t become resistant, no need for chemicals
Disadvantges: predator could leave area, predator might not eat pest