Biology, Bionenergetics

Question 1

Label the main organs of a plant and describe their functions.

Answer 1

Main organs of a plant … Leaves, stems, roots, flowers

Their Functions … Leaves perform photosynthesis. Stems transport and store water and nutrients. Roots absorb minerals, water, and store nutrients. Flowers contain reproductive structures

Question 2

Identify the tissues in a leaf and describe their functions. Relate the structure of each tissue to its function in photosynthesis.

Answer 2

Tissues in a leaf … Epidermis, Palisade Mesophyll, Spongy Mesophyll,

Their functions:

Epidermis:

… Allows light to go into the leaf. Because it is thin and transparent

Palisade mesophyll:

… Contains lots of chloroplasts which do photosynthesis

Spongy mesophyll:

… Diffuses gases. To do this, it has big air space and large surface area

Question 3

Explain why there are more stomata on the lower surface of a leaf.

Answer 3

… Diffusion of carbon dioxide into the leaf for photosynthesis and oxygen and water vapour out of the leaf, is greatest when the stomata are open during the day. Stomata are found mainly on the lower surface of the leaf to reduce water loss by transpiration.

Question 4

Describe the role of stomata and guard cells to control water loss and gas exchange.

Answer 4

… The stomata control gas exchange in the leaf. Each stomata can be open or closed. In the light, the guard cells absorb water by osmosis , become turgid (swollen from water uptake), and stomata open. In the dark, the guard cells lose water, become flaccid and stomata close.

Question 5

Calculate stomatal density.

Answer 5

… Area = πr²

Question 6

Describe the organs that make up the plant transport system.

Answer 6

… Plant Transport system:

• Xylem
• Phloem
• Root hair cells

Question 7

Describe the role of xylem, phloem and root hair cells and explain how they are adapted for their functions.

Answer 7

Role of xylem:

… Transports water and mineral salts from the roots up to other parts of the plant. It has a continuous, hollow tube which allows for this to happen

Role of phloem:

… Transports sucrose and amino acids up and down the plant. It has tubes with a perforated end

Role of root hair cells:

… Uptakes water and minerals. They are long and thin so they can penetrate between soil particles, and they have a large surface area for absorption of water

Question 8

Define the terms ‘transpiration’ and ‘translocation’.

Answer 8

Transpiration … The evaporation of water at the surfaces of the spongy mesophyll cells in leaves, followed by loss of water vapour through the stomata

Translocation … The movement of sugar produced in photosynthesis to all other parts of the plant for respiration

Question 9

Define the term ‘active transport’.

Answer 9

… The movement of dissolved molecules into or out of a cell through the cell membrane, from a region of lower concentration to a region of higher concentration

Question 10

Describe where active transport occurs in humans and plants and what is transported.

Answer 10

Humans:

… Uptake of glucose by epithelial cells in the villi of the small intestine

Plants:

… Uptake of ions from soil water by root hair cells

Question 11

Explain why active transport requires energy.

Answer 11

… The particles move against the concentration gradient. This requires using energy released during respiration

Question 12

Explain how active transport enables cells to absorb ions from very dilute solutions.

Answer 12

… Ions are moved into root hairs, where they are in a higher concentration than in the dilute solutions in the soil. Active transport then occurs across the root so that the plant takes in the ions it needs from the soil around it.

Question 13

Explain the relationship between active transport and oxygen supply and numbers of mitochondria in cells.

Answer 13

… Active transport takes place in cells that normally have many mitochondria. They release energy, which is needed for active transport. Aerobic respiration occurs in mitochondria, releasing energy

Question 14

Test to see if a leaf contains starch.

Answer 14

… 1. Cover part of the leaf and leave it overnight

2. Put it in boiling water (stops reactions in cells)
3. Remove chlorophyll and boil in alcohol
4. Use iodine to test for starch

Question 15

Explain why the leaves are tested for starch and not for sugar.

Answer 15

… Leaves quickly convert glucose to starch. Leaves are tested for starch to show that photosynthesis has happened.

Question 16

Describe the test for oxygen.

Answer 16

… A piece of pondweed is put in a test tube containing tap water and placed by a light source. You count the bubbles evolved from the pondweed per a certain amount of time e.g 1 minute

Question 17

Interpret results and relate to photosynthesis equation.

Answer 17

… The more bubbles produced, the higher the rate of photosynthesis. The bubbles are bubbles of oxygen. Oxygen is formed from the ingredients in the photosynthesis.

Question 18

State factors that can limit the rate of photosynthesis.

Answer 18

… Factors that limit the rate of photosynthesis:

• Temperature
• Light intensity
• CO2 concentration

Question 19

Interpret data showing how factors affect the rate of photosynthesis.

Answer 19

Temperature:

… As temperature increases, photosynthesis increases up to an optimum temperature. After this enzymes are denatured, so photosynthesis stops. (Because photosynthesis needs enzymes)

Light intensity:

… Increasing light, increases photosynthesis up to the point where something else limits it e.g temperature, CO2

CO2 concentration:

… Increasing CO2, increases photosynthesis up to the point where something else limits it e.g temperature, light

Question 20

Interpret graphs to decide which factor is limiting the rate.

Question 21

Explain how conditions in greenhouses can be controlled to optimise the growth of plants.

Answer 21

… - Use artificial light to increase day length in green houses
- Increasing temperature using artificial heating
- Increasing CO2 to an appropriate level can increase the
rate of plant growth

Question 22

Evaluate the benefits of artificially manipulating the environment in which plants are grown.

Answer 22

… There is a better and bigger crop quality. There is quicker crop growth so food price is decreased as there is more food available

Question 23

List ways in which glucose is used by a plant.

Answer 23

… For energy and to make other substances e.g cellulose and starch

Question 24

Describe functions of fats, oils, cellulose, starch and proteins in a plant.

Answer 24

… Functions of Fats:

 - Plants use fats to store energy 

Oils:

  - Used to store energy 

Cellulose:

   - Keeps the structure of plant cell walls stable

Starch:

   - Stored as energy in the form of glucose

Proteins:

    - Used for immunity, and to meet the growth and nutritional 
      demands of developing seedlings

Question 25

Explain how plants obtain nitrate ions and what they are needed for.

Answer 25

… Plants absorb nitrates in water through their roots. Nitrate ions are needed to make proteins for healthy growth

Question 26

Interpret data from the results of bicarbonate indicator experiment.

Answer 26

< go to document, and cover conditions in plant column to test your knowledge >

Question 27

State that all animals and plants produce_______.

Answer 27

… All animals and plants produce carbon dioxide and water all the time as a consequence of aerobic respiration

Question 28

Write the word equation for aerobic respiration.

Answer 28

… Glucose + Oxygen ———–> Carbon Dioxide + Water + Energy

Question 29

Define the term ‘aerobic’.

Answer 29

… A type of respiration which requires oxygen. The chemical process by which an organism obtains energy.

Question 30

Describe what organisms need energy for.

Answer 30

… To grow, maintain their structures, to keep warm, and for chemical reactions to build larger molecules

Question 31

State the site of aerobic respiration and be able to give examples of cells that contain a lot of mitochondria

Answer 31

… Site of aerobic respiration:

- Mitochondria

Examples of cells that contain a lot of 
mitochondria:

 - Muscle cells, liver cells

Question 32

Define the term ‘anaerobic

Answer 32

… A type of respiration which does not require oxygen. When oxygen is absent, cells release a small amount of energy by the breakdown of food substances in the absence of oxygen

Question 33

Explain why anaerobic respiration is less efficient than aerobic respiration.

Answer 33

…

• Anaerobic respiration releases much less energy from glucose compared to aerobic respiration
• Lactic acid is a poisonous waste product

Question 34

Write the word equation for anaerobic respiration in animal cells.

Answer 34

… Glucose ———–> Lactic acid + Energy

Question 35

Write the word and symbol equation for anaerobic respiration in yeast cells.

Answer 35

Glucose ———-> Ethanol + CO2

C6H12O6 ———-> 2C2H5OH + 2CO2

Question 36

State that anaerobic respiration in yeast is called_______.

Answer 36

… Anaerobic respiration in yeast is called fermentation

Question 37

Explain why yeast is used to make bread and alcoholic drinks

Answer 37

… Yeast uses anaerobic respiration and the products of that are ethanol and carbon dioxide. Ethanol is used to make alcohol. And CO2 bubbles are produced when bread is baking. These CO2 bubbles make bread rise.

Question 38

Describe and explain the changes that occur in the body during exercise.

Answer 38

…

• Heart rate increases
• Breathing rate increases
• Glucose and oxygen go to the cells which are used for respiration
• Energy is released and used for muscles.
• Muscles break down the lactic acid that is made.
• Lactic acid is made due to your body changing to anaerobic respiration during exercise.

Question 39

Describe the effects of long periods of vigorous exercise on the body.

Answer 39

… Lactic acid levels build up, glycogen reserves in the muscles become low as more glucose is used for respiration, and additional glucose is transported from the liver

Question 40

Define the term ‘oxygen debt’

Answer 40

… The amount of oxygen required to remove the lactic acid.

Question 41

Explain what happens to lactic acid once exercise stops.

Answer 41

… It is converted to glucose, then glycogen

Question 42

Define the term ‘metabolism’.

Answer 42

… All the chemical reactions happening in the body, not just in digestion

Question 43

Give examples of reactions in metabolism.

Answer 43

…

• The conversion of glucose to starch,
  glycogen
• The formation of lipids
• The formation of amino acids and proteins
• Respiration

Question 44

Name some chemicals formed from glucose molecule.

Answer 44

…

- Carbon dioxide
- Water
- Energy

Question 45

Describe the function of glucose and nitrate ions when forming amino acids, which form proteins.

Answer 45

… Glucose is joined with nitrates absorbed from the soil to make amino acids . These are joined together to make proteins

Question 46

Describe the formation of urea.

Answer 46

… When excess amino acids are broken down, urea is produced in the liver