Plants Chapter 6 Test

Question 1

How can We describe photosynthetic organisms as?

Answer 1

The main producers of food and therefore biomass

Question 2

What is photosynthesis in plants and algae?

Answer 2

An endothermic reaction that used light energy to react carbon dioxide and water to produce glucose and oxygen

Question 3

Explain the effect of temperature as a limiting factor on the rate of photosynthesis

Answer 3

Temperature + rate of photosynthesis = proportional increase.

Colder= little particle movement means it's to cold to catalyse the process 
Hotter= enzymes denature (above 40*)

Higher temp= more collisions between enzymes and substrate (lock and key)

Question 4

What is a limiting factor?

Answer 4

The factor directly affects the rate of photosynthesis on its own regardless of the level of the other factors.
Limit the amount of photosynthesis able to happen

Question 5

What are the major limiting factors for photosynthesis

Answer 5

Light intensity - 1st limiting factor, can’t begin without light
Temperature
Carbon dioxide levels

Question 6

Optimum temperature for photosynthesis

Answer 6

Between 10-20*

Question 7

How can we tell from a graph when the limiting factor has changed?

Answer 7

When curved graph creates/changes to a straight line something else has become the limiting factor because the previous one now has enough, working at a suitable rate.

Question 8

What are commercial used of auxins, gibberellins and ethene in plants

Answer 8

Auxins- used in weedkillers and rooting powders

Gibberellins- in germination, fruit and flow formation and the production of seedless fruit

Ethene- fruit ripening

Question 9

What is the calculation for rate for transpiration?

Answer 9

Used within experiment with exploring rates of transpiration…

Distance moved by the air bubble / time taken for the air bubble to move that distance

Question 10

How are plants adapted to survive in extreme environments

Answer 10

Waxy cuticle- allows excess rainwater to fall off
Size of stomata opening- can be altered by the plant in response to the availability of water and light intensity
Bigger surface area= more sunlight
Pointed drip tips -allow excess rainwater to fall off
Thin, flat, spongy mesophyll layer allow water loss

Question 11

How do plant hormones control and coordinate plant growth and development?

Answer 11

Auxins is a plant hormone produced at tips of stems and roots and controls direction of growth of root tips and stem tips in response to different stimuli including light and gravity.

Question 12

Role of auxins in phototropism and gravitropism

Answer 12

Phototropism- growth in response to the direction of light

Gravitropism- growth in response to the direction of gravity

Light and gravity can interfere with the transport of auxin causing it to be unevenly distributed

Question 13

What does auxin do?

Answer 13

Moved in a solution to older parts of the stem and roots where it changes the elasticity of the cells. More elastic cells absorb mor at the and grow longer causing it to bend in the stem or root.

Question 14

How is the structure of the root hair cells adapted to absorb water and mineral ions

Answer 14

A large surface areas to speed up osmosis

Question 15

How are the structures of the xylem and phloem adapted to their function in the plant

Answer 15

Lignified dead cells in xylem transport water and minerals through the plant

Living cells in phloem use energy to transport sucrose around the plant

Question 16

How water and mineral ions are transported through the plant by transpiration?

Answer 16

Water is absorbed from the soil and through root hair cells
Water moves by osmosis from root cell to root cell until it reaches the xylem
It is transported through the xylem vessels up the stem to the leaves
It then evaporates from leaves (transpiration) opening and closing of stomata is controlled by guard cells and can control rates of transpiration.

Question 17

How does sucrose get transported around the plant by translocation

Answer 17

Phloem transports sucrose and amino acids up and down the plant. This is called translocation ( a transport of dissolved material within a plant )
In general this happens between where these substances are (the sources- leaves) and where they are used or stored (the sinks- growing shoot or roots)

Question 18

Explain how the structure of the leaf is adapted for photosynthesis and gas exchange
EXTERNAL!!!!!!

Answer 18

Large surface area- absorb more light
Thin- short distance for co2 to diffuse into leaf cell
Chlorophyll- absorbs sunlight to transfer energy into chemicals
Stomata- allow co2 to diffuse into leaf

Question 19

Explain how the structure of the leaf is adapted for photosynthesis and gas exchange
INTERNAL!!!!

Answer 19

thin cuticle - protect leaf without blocking light
Palisade cell layer at top of leaf- absorb mor light
Spongy layer- air spaces allow co2 to diffuse through the lead and increase surface area
Palisade contains many chloroplasts- to absorb all available light

Question 20

What is the equation for photosynthesis and how do we balance It?

Answer 20

CO2 + H2O ——–> C6H12O16 + 6O2

Balance- add a 6 in front of Carbon dioxide, water and oxygen

Question 21

How does a cacti survive in its extreme conditions? (2 points)

Answer 21

Stomata only open at night and CO2 is taken in at night and store for use during the day
Thick cuticle
Have spines instead of leaves which minimises the surface area and reduces water loss by transpiration
Roots have a large surface area

Question 22

Explain the effect of light intensity on the rate of photosynthesis EXPERIMENT

Answer 22

Measure length of pondweed with ruler
Measure 200ml of water into beaker
Place pondweed into beaker
Use ruler to measure different distances away from light
Count how many bubbles of oxygen leave pondweed per minute

Question 23

What can effect the rate of water uptake by a plant?

Answer 23

Light intensity- more light is more transpiration and less light is less transpiration- can’t evaporate
Air movement- faster in windy conditions- changes pressure on leaf
Temperature- higher=more transpiration lower=less transpiration

Question 24

How can humidity effect uptake of water? Transpiration

Answer 24

Slower in humid conditions, diffusion of water out of leaf slows down if leaf is already surrounded by moist air

It increases concentration gradient because diffusion of water from inside plant to outside the plant through stomata will be increased.

Question 25

What is the effect of light intensity on photosynthesis

Answer 25

On a graph is directly proportional- up then straight.
Without enough light a plant cannot photosynthesise very quickly, even if there is plenty of water and CO2. Increasing the light intensity will increase speed of photosynthesis

Question 26

What is the Effect of Carbon dioxide on the rate of photosynthesis

Answer 26

On a graph is directly proportional- up then straight.
Carbon dioxide needs to react with water to form the products of photosynthesis- oxygen and glucose.
A plant cannot photosynthesise if there is insufficient CO2

Question 27

How is a Xylem adapted to transport water

Answer 27

Xylem cell has a thick cell wall which provides strength
Lignin - supportive structure and prevents the xylem from collapsing under pressure from the water
Lignin- waterproof to prevent any water from diffusing out of the xylem

Question 28

What is a tropism

Answer 28

A growth in response to a stimuli, plants grow towards sources of water and light which they need to survive and grow.
Gravitropism
Phototropism

Question 29

What is active transport and what does move

Answer 29

The movement of dissolved molecules (minerals) move across a cell membrane from a lower concentration to a higher concentration. In active transport, particles move against the concentration gradient and therefore require an input of energy from cell

Question 30

What is osmosis and what does it move

Answer 30

Osmosis is movement of WATER from a high concentration to a lower concentration of water
OR can be said as
Diffusion of water from a dilute solution to a concentrated solution through a partially permeable membrane.

Question 31

What is diffusion in plants

Answer 31

Movement of particles in and out of cells down a concentration gradient (from high concentration to low concentration)
Eg- movement of carbon dioxide in leaves

Question 32

What is the inverse square law calculation

Answer 32

Light intensity= 1 / distance2 in meters

Eg- plant is 20cm away from light

1/0.2m2 = 25 arbitrary units

Question 33

What is the inverse square law calculation

measured in?

Answer 33

Arbitrary units

Question 34

What are sieve cells in translocation

Answer 34

A Sieve tube has sieve cells which have pores in which nutrients can flow from cell to cell, it lacks most organelles so therefore the companion cell which contains them controls the movement of solutes