Unit 3: Plant Nutrition and Transport

Question 1

What is photosynthesis

Answer 1

Photosynthesis is the process of converting carbon dioxide and water into glucose and oxygen using sunlight

Question 2

What is the word equation for photosynthesis

Answer 2

Carbon dioxide + Water —> Glucose + oxygen

Question 3

Write the chemical equation for photosynthesis

Answer 3

6CO2 + 6H2O —> C6H12O6 + 6O2

Question 4

Name all the oeganelles found in a plant cell

Answer 4

• Waxy cuticle
• upper epidermis
• palisade mesophyll layer
• spongy mesophyll layer
• vascular bundle
• lowe epidermis
• air space
• guard cells
• stoma

Question 5

How are leaves adapted for Efficient photosynthesis

Answer 5

• Leaves are broad so they have a large surface area to absorb more light
• Most of the chloroplast is found in the palisade layer which is at the top, meaning they can absorb the most light
• The upper epidermis is transparent so that light can pass through it to the palisade layer
• Leaves have a xylem and phloem to deliver water and other nutrients to every part of the leaf and take away glucose produced by photosynthesis, they also help to support the leaf structure
• The waxy cuticle helps to reduce water loss by evaporation
• The lower surface contains stomata that lets CO2 diffuse directly into the leaf

Question 6

What three things affect the rate of photosynthesis

Answer 6

• Light
• CO2
• Temperature

Question 7

Describe an experiment to test a leaf for starch

Answer 7

• Dunk the leaf in boiling water (hold it with tweezers or forceps). This will denature the enzymes and stop any chemical reactions from happening inside the leaf
• Put the leaf in a boiling tube with some ethanol and heat it in an electric water bath until it boils, this will get rid of any chlorophyll and make the leaf a white-ish colour
• Rinse the leaf in cold water and add a few drops of iodine solution, if starch is present the leaf will turn blue black

Question 8

What does the iodine in a starch test turning blue-black indicate

Answer 8

• If the iodine is blue-black then the leaf can photosynthesize
• If the iodine doesn’t change colour then the leaf can’t photosynthesize

Question 9

What is the function of nitrogens in plants and what does a plant look like when it lacks nitrogen

Answer 9

• Nitrogen makes amino acids and proteins which are needed for cell growth
• If a plant lacks nitrogen the plant becomes stunted and the older leaves will turn yellow

Question 10

What is the function of phosphates in plants and what does a plant look like when it lacks phosphate

Answer 10

• Phosphate makes DNA and cell membranes, they are also needed for respiration and growth
• Lack of phosphate have poor root growth and their older leaves turn purple

Question 11

What is the function of potassium in plants and what does a plant look like when it lacks potassium

Answer 11

• Potassium helps the enzymes needed for photosynthesis and respiration
• Lack of potassium causes poor fruit growth and discoloured leaves

Question 12

What are the two main transport systems in plants and what do they each transport

Answer 12

• Xylem: Carries water and mineral salts from the roots up the shoot to the leaves in the transpiration stream
• Phloem: Transports sugars like sucrose and amino acids from where they were made in the leaves to other parts of the plant

translocation: The movement of food substances across a plant

Question 13

How are root hair cells adapted to take in water

Answer 13

• They have a large surface area to absorb water
• They have a lower concentration of water than the soil, allowing water to enter the root hair cells by osmosis

Question 14

What is transpiration

Answer 14

The loss of water from a plant

Question 15

How is transpiration caused

Answer 15

Transpiration is caused by the evaporation and diffusion of water from a plants surface

Question 16

Where does transpiration occure most frequently

Answer 16

At the leaves

Question 17

What do plants do to overcome transpiration

Answer 17

• The slight shortage of water due to transpiration causes more water to be drawn up through the xylem vessels to replace it
• This in turn causes more water to be drawn from the roots

This process isn known as a transpiration stream

Question 18

What are the four main factors that affect transpiration rate

Answer 18

• Light intensity
• Temperature
• Wind speed
• Humidity

Question 19

How does light intensity affect transpiration rate

Answer 19

• The brighter the light, the greater the transpiration rates
• When it is dark the stomata begins to close because photosynthesis cannot occure in the dark and the plant therefore doesn’t need CO2
• This causes less water to escape the closed stomata

Question 20

How does temperature affect transpiration rate

Answer 20

• The warmer it is, the greater the rate of transpiration
• This is because water can evaporate faster

Question 21

How does wind speed affect transpiration rate

Answer 21

• The greater the wind speed the greater the transpiration rate
• This is because when its more windy the water vapour is swept away, maintaining low concentration of water in the air outside the leaf
• This causes diffusion in the leaf to occure faster

Question 22

How does humidity affect transpiration rate

Answer 22

• The drier the air around a leaf, the faster transpiration occurs
• This is because the drier the area the lower the concentration of water around the plant is
• This causes diffusion to happen faster

Question 23

Describe an investigation to estimate transpiration rate

Answer 23

• A potometer would be used to estimate transpiration
• Cut a shoot underwater to prevent air from entering the xylem
• Assemble the potomenter in water aand insert the shoot under water so no air can enter
• Remove the apparatus from the water but keep the end of the capillary tube submerged into a beaker of water
• Check the apparatus is watertight and not airtight
• Dry the leaves, allow time for the shoot to acclimatise and then shut the tap
• Remove the end of the capillary tube from the beaker of water until one air bubble has formed, then put the end of the tube back into the water
• Record the starting position of the air bubble
• Start a stopwatch and record the distance moved by the bubble per unit time
• Keep the conditions constant thoughout the experiment

Cut the shoot in a slant to increase surface area