1. Cellular Nutrition BZ 67 - 75
These notes are summaries of the BZ information and the answers are provided, but there is not enough time in class to discuss and copy all answers so you will need to download the notes from the Biology wiki .

2. BZ 67 Modes of nutrition
Auto – self, Hetero – others, Trophic – related to feeding or eating, therefore – ‘Self-feeders’ and ‘feeders on others’.
Autotrophs – synthesise their food in specialized cell organelles eg photo-autotrophs and chemo-autotrophs.
Photo-autotrophs – use light energy and carbon dioxide to produce food eg plants, algae, cyanobacteria
Chemo-autotrophs – use inorganic compounds eg hydrogen sulfide and carbon dioxide to make their food – mainly archaea in hot, acidic or ‘no light’ environments
Heterotrophs – (chemo-heterotrophs) rely on glucose from plant, dead material or other animals eg some bacteria and protists, all animals and fungi.

3. BZ 67 Ans

4. Autotrophs – don’t draw
Hydrothermal vents
Chemoautotrophs are mostly bacteria or archaea that live in hostile environments such as deep sea vents. They are the primary producers in such ecosystems.

5. Heterotrophs - don’t draw

6. BZ 68 Energy in photosynthetic cells
Photosynthesis stores energy – plants only.
Cellular respiration releases energy – plants and animals.
The energy from sunlight is captured and stored as glucose in Chloroplasts, which powers the production of ATP in Mitochondria.
ATP has high energy bonds that store and release energy in cellular processes.
Cellular respiration provides the energy to restore ATP from ADP and Pi

7. BZ 68 Ans

8. Draw this diagram

9. Draw this diagram
ATP and heat

10. BZ 69 Plants as producers
Photosynthesis by autotrophs (plants) directly and indirectly sustains heterotrophic life on Earth.
Requirements for photosynthesis
Light energy from the sun
Chlorophyll – absorbs the light
Carbon dioxide to convert to carbohydrates
Water to hydrate the carbon atoms

11. BZ 69 Ans

12. BZ 70 Photosynthesis
Photosynthesis is the process of converting sunlight, carbon dioxide and water into glucose and oxygen.

13. BZ 70 Ans

14. BZ 71 & 72 Leaf structure Leaves are the main site of photosynthesis.
Adaptations that aid photosynthesis
The upper surfaces ie the Cuticle and Upper Epidermis protect the deeper cells from high temperatures and evaporation.
The middle mesophyll cells contain chlorophyll for photosynthesis and air spaces that allow for the quick exchange of gases
Lower Epidermis contains stomata (small pores) that regulate gas exchange and fluid loss.
Leaf veins contain Xylem (water transport) and Phloem (food transport)

15. BZ 71 Ans

16. BZ 72 Ans

17. BZ 73 Factors affection Photosynthesis
Environmental factors significantly affect the rate of photosynthesis.
Photosynthesis is increased by:
Higher CO2 levels
Higher light levels
Higher temperatures
Photosynthesis is decreased by:
High wind conditions – increases water loss
Low water conditions.

18. Socrative Open Question - Short Ans.
Light intensity
Socrative Open Question - Short Ans.
If you had to spend money to increase the light intensity from 2 to 4, or from 4 to 6, which would give you the best cost/benefit? Explain your decision.
2-4 = 20% increase
4-6 = 2-3% increase

19. Socrative Open Question - Short Ans.
Why are there natural limits to increases in CO2 concentration and temperature? Explain your response to each change.
Plants can only consume as much CO2 as there is sunlight and water to react with it.
Extra CO2 may combine with water to form weak carbonic acid that can denature proteins and damage enzymes as can high temperatures.

20. BZ 73 Ans

21. BZ 74 Controlled environments
If all abiotic factors are optimal, then optimal growth rates will be achieved. When one factor is low, it limits the other factors, but too much of any factor can be toxic.
Temperature
CO2
Light
Water
Fertilizer
Lack of wind

22. BZ 74 Ans

23. BZ 74 Ans