Bioenergetics topic 4 biology

Photosynthesis uses energy to? This takes place in? Energy is transferred to? What kind of process is it?

1. photosynthesis uses energy to change carbon dioxide & water into glucose & oxygen

2. takes place in chloroplasts in green plant cells (contain pigment like chlorophyll that absorb light)

3. Energy transferred to chloroplasts from environment by light

4. Endothermic → energy transferred from environment in process

Word & symbol equation for photosynthesis

1. Carbon dioxide + water → (light) glucose + oxygen

2. 6CO₂+6H₂O → (light) C₆H₁₂O₆+6O₂

what do plants use glucose for in 5 main ways

1. respiration → transfers energy from glucose, enables plants convert the rest into various other useful substances

2. Making cellulose → converted into cellulose for making strong cell walls (plant)

3. making amino acids → combined with nitrate ions (absorbed from soil) to make amino acids, then turn to proteins

4. Stored as oils or fats → turned into lipids for storing in seeds

5. Stored as starch → turned into starch & stored in roots, stems & leaves ready for when photosynthesis isn’t happening (winter). Starch is insoluble makes better for storing than glucose (cell with lots glucose would draw lots water & swell up)

3 limiting factors for photosynthesis? What are 3 environmental conditions that limit photosynthesis? How can chlorophyll be a limiting factor?

1. limiting factors (stopping photosynthesis from happening faster) → light intensity, CO₂ concentration, temperature

2. Combined effect on rate of photosynthesis, which limits at particular time depends environmental conditions:

   • Night → light

   • Winter → temperature

   • Warm & bright enough → CO₂ concentration

     3. Chlorophyll can be limiting factor → amount affected by disease/ environmental stress (lack nutrients), become damaged/not make enough chlorophyll, rate reduced → cant absorb as much light

Light provides? Lights level increased? After a while? In a lab? need to measure?

1. light provides energy (photosynthesis),

2. Light level raised = rate increases steadily (only to certain point)

3. light intensity increases = rate no longer increases → either temperature/ CO₂ level now limiting factor

4. in lab can change light intensity (moving lamp)

5. need measure plant using light meter/ maths to get result

Whats CO₂ needed for? What causes the graph to flatten? What would the limiting factor then be?

1. CO₂ = raw materials needed photosynthesis

2. amount CO₂ only increases rate up to point the graph flattens. CO₂ increases rate, if no longer increase = CO₂ no longer limiting factor

3. Light & CO₂ plentiful supply, factor limiting = temperature

Usually if temp is a limiting factor because? If the plant is too hot?

1. Usually if temperature is limiting factor becuase too low → enzymes needed photosynthesis work more slowly at low temp

2. Plant too hot = enzymes needed & other reactions are damaged → happens about 45C

At the start? Lines even off when?

1. at start both lines show light intensity increase = rate increases steadily

2. But lines even off when light no longer limiting factor, line at 25C levels of at higher point than 15C, temperature must have been limiting factor at 15C

Both lines level off when? compare the 2 lines.

1. both lines level off when light is no longer limiting factor

2. line at higher CO₂ concentration of 0.4% levels off at higher point than 0.04%, means CO₂ concentration limiting factor at 0.04% CO₂, aint temperature because same for both lines (25C)

Oxygen production shows rate of photosynthesis practical (Pondweed practical)

Canadian pondweed → measure effect light intensity on rate of photosynthesis, produces oxygen (faster rate oxygen production = faster rate)

1. Source white light placed at specific distance from pondweed

2. left to photosynthesise for set amount time, as photosynthesises oxygen released collect in capillary tube

3. End of experiment, syringe used draw gas bubble in tube alongside ruler & length of gas bubbles measured, proportional to volume of O₂ produced

4. Any variables that affect results should be controlled (temperature & time)

5. Experiment repeated 2 with light source at same distance & mean volume of O₂ produced is calculated

6. then whole experiment repeated with light source at different distances from pondweed

(Pondweed practical) When the lamp is moved away? If the distance decreases? Light intensity decreases in proportion to? Inverse square law?

1. lamp moved away pondweed = amount of light reaches pondweed decreases

2. distance decreases = light intensity increases (inversely proportional)

3. light intensity decreases in proportion to square of distance → inverse square law written → light intensity ∝ 1/ distance (d)²

4. inverse square law → halve distance, light intensity is 4x greater

ideal artificial environment for plants? Why? Light is always needed for photosynthesis? How do you increase CO₂ levels? Keeping plants enclosed means? It costs mean for?

1. ideal artificial environment for plants to grow in greenhouse

2. help trap suns heat & make sure temperature doesn’t become limiting. winter = too cold (use heater keep temperature at ideal level), summer = too hot (use shades & ventilation)

3. Light always needed photosynthesis, often supply artificial light after sun sets (+ quality photosynthesis time)

4. increase CO₂ level (paraffin heater heat greenhouse, as burns = makes CO₂ by-product)

5. Keeping plants enclosed = free from pests & diseases, add fertilisers to soil (provide minerals healthy growth)

6. Costs money → keep conditions just right photosynthesis = plants grow faster & decent crop harvested + often = sold), important not more light, CO₂, nutrients than plants need (waste money)

Whats respiration? Where does it happen? What kind of reaction is it?

1. Respiration → process of transferring energy from (breakdown of) glucose (sugar) & goes in every cell in body continuously

2. Happens in plants too all living organisms respire → how they transfer energy from food to cells

3. Exothermic → transfers energy to environment

3 examples of why respiration transfers energy

1. build up large molecules from smaller ones (proteins from amino acids)

2. in animals → used to allow muscles to contract (move about)

3. in mammals & birds → used to keep body temperatures steady in cooler surroundings

What happens in cells? Many reactions are linked together to? What is the sum of all those reactions called?

1. in cells → lots chemical reactions happening all time, controlled by enzymes

2. many reactions linked together to form bigger reactions:

   reactant — (enzyme) → product — (enzyme) → product — (enzyme) —> product

3. Sum of all those reactions that happen in cell or body is called metabolism

3 substances that lots of small glucose molecules are joined together to make? What are lipid molecules each made from? What is a protein made from?

1. lots small glucose molecules are joined together in reactions to form starch (storage molecule in plant cells), glycogen (storage molecule in animal cells) & cellulose (component of plant cell walls)

2. Lipid molecules each made from one molecule of glycerol & 3 fatty acids

3. glucose combined with nitrate ions to make amino acids, then made into protein

Glucose is broken down in respiration which produces? Excess protein is broken down to produce?

1. Glucose broken down in respiration → transfers energy to power all reactions in body that make molecules

2. excess protein is broken down in reaction to produce urea → then excreted in urine

What’s the most efficient way to transfer energy from glucose? Goes on all? Most of reactions happen in? Word & symbol equation

1. Most efficient way to transfer energy from glucose is aerobic respiration

2. goes on all the time in plants & animals

3. Most of reactions in aerobic respiration happen inside mitochondria

4. Word & symbol equation:

   Glucose + oxygen → carbon dioxide + water

   C₆H₁₂O₆+6O₂→6CO₂+6H₂O

Whats anaerobic respiration? word equation? doesn’t transfer nearly as much? Only used in?

1. Anaerobic → without oxygen = incomplete breakdown of glucose making lactic acid

2. Word equation:

   Glucose → lactic acid

3. doesn’t transfer nearly as much energy as aerobic, because glucose isn’t fully oxidised (don’t combine with oxygen)

4. only used in emergencies

Plant & yeast cells respire without oxygen? word equation? Whats anaerobic respiration called in yeast cells? In the food & drinks industry used to make? In bread-making what makes it rise? Whats beer & wine-making?

1. plant & yeast cells respire without oxygen but produce ethanol (alcohol) & carbon dioxide

2. Word equation:

   glucose → ethanol + carbon dioxide

3. anaerobic respiration in yeast cells → fermentation

4. food & drinks industry, fermentation by yeast = great value used make bread & alcoholic drinks (beer & wine)

5. bread-making → carbon dioxide from fermentation that makes bread rise

6. beer & wine-making → fermentation process produces alcohol

Muscles need energy from respiration? Increased respiration in cells means? What increases? Really vigorous exercise means? Not best way to transfer energy because? Long periods of exercise cause?

1. muscles need energy from respiration (contract). exercise → muscles contract more frequently than normal = need more energy →> from increased respiration

2. increase respiration in cells means need more oxygen

3. breathing rate & breath volume increases (+oxygen into blood) & heart rate increases to get oxygen faster round body. Remove CO₂ quicker at same time

4. Really vigorous exercise (sprinting) body cant supply oxygen to muscles quick enough → start respiring anaerobically

5. Not best way to transfer energy from glucose, lactic acid builds up in muscles (painful)

6. Long periods of exercise → muscle fatigue → muscles get tired & stop contracting efficiently

When you stop exercising? Why do we repay oxygen? What does this mean? Why do pulse & breathing rate stay high? Whats another way of coping with high levels of lactic acid?

1. when stop exercising → oxygen debt → amount of extra oxygen body needs to react with build up of lactic acid & remove from cells (oxygen +lactic acid → CO₂ + water)

2. have to repay oxygen didn’t get to muscles in time because lungs, heart & blood couldn’t keep up with demand

3. means have to keep breathing hard for awhile after stop to get more oxygen into blood → transported to muscle cells

4. pulse & breathing rate stay high = high levels of Lactic acid & CO₂

5. Another way of coping with high levels lactic acid → blood that enters muscles transports lactic to liver, lactic acid converted back to glucose

How do you measure the breathing rate? If the pulse rate increases? How to reduce effect of random errors?

1. measure breathing rate by counting breaths & heart rate by taking pulse & plot bar chart

2. pulse rate increases =more intense exercise is, body need more oxygen to muscles & take more CO₂ away

3. Reduce effect of random errors on results, do as group & plot average pulse rate for each exercise