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 .

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.

BZ 67 Ans

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.

Heterotrophs - don’t draw

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

BZ 68 Ans

Draw this diagram

Draw this diagram ATP and heat

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

BZ 69 Ans

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

BZ 70 Ans

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)

BZ 71 Ans

BZ 72 Ans

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.

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

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.

BZ 73 Ans

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

BZ 74 Ans

BZ 74 Ans