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GCSE OCR 21st Century BIOLOGY Using Food and Controlling Growth Complete Revision Summary

Using Food and Controlling Growth

Using Food and Controlling Growth

• Cellular respiration

• Aerobic and anaerobic respiration

• Metabolism

It is the process of breaking down food to release energy.

AEROBIC RESPIRATION

• Takes place in the presence of Oxygen
• Releases more energy and the food is completely broken down.
• Takes place in the mitochondria
• It is opposite of photosynthesis

ANAEROBIC RESPIRATION

• Takes place in absence of oxygen.
• Releases less energy and food is not completely broken down.
• Takes place in the Cytoplasm
• Glucose + Oxygen Carbon Dioxide + Water
• C₆H₁₂O₆ +60₂ 6CO₂ + H₂O

PLANTS

• known as fermentation
• forms ethanol and carbon-dioxide
• Glucose Ethanol + Carbon Dioxide

ANIMALS

• takes place in muscles
• Glucose Lactic Acid

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BREATHING AND RESPIRATION

EXOTHERMIC

As it releases heat.

The energy released in making carbon dioxide and water is more than the energy taken in to break glucose and oxygen

Cristae are the folding of the inner membrane of the mitochondria to increase the surface area for the attachment of the enzymes

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WHY WE NEED ENERGY

MOVEMENT

• Energy is required by the muscles to contract.
• Respiration provides energy for muscle contraction.
• Muscle cells have loads of mitochondria and glycogen for efficient respiration.

TRANSPORT

• Transport of substance in an out of the cell against the concentration gradient via active transport required energy.

THERMOREGULATION

• Respiration produces heat which helps to maintain the body temperature.

CATABOLISM

• Breaking of large substances to smaller ones like digestion requires energy.

ANABOLISM

• Building of bigger molecules from smaller ones like making proteins fats and lipids from minerals ions require energy

RESPONSE TO EXERCISE

Demand for oxygen and glucose increases as more energy is needed

BREATHING RATE

• The breathing rate increases so that more oxygen is inhaled to meet the demands of oxygen by the muscles.
• Increased breathing rates also increases the rate of removal of carbon dioxide.

HEART RATE

• Increase heart rate pumps more blood to the muscles.
• Increase blood supply increases the supply of both glucose and oxygen via blood to the muscles cells.

GLYCOGENOLYSIS

• Glycogen       Glucose
• Stored carbohydrates, glycogen is converted to glucose in the muscles during exercise to meet the demand for increased glucose.

WHY BREATHlNG RATE Б НОН AFTER STOPPlNG ТНЕ EXERClSE

Extra Oxygen needed by the body after exercise to recover.

OXYGEN DЕВТ*

• During Exercise the body switches to anaerobic respiration. So glucose is broken down into lactic Acid
• Glucose        Lactic Acid
• The lactic acid needs to be broken down into carbon dioxide. The breathing rate is still high to get maximum oxygen to break lactic acid.
• Lactic acid + O₂                       CO₂ + H₂O

METABOLISM

It is the sum of all the reactions of the body

CATABOLISM

Breakdown reaction in which bigger molecule is broken down into smaller ones.

1. a) Breakdown of glycogen
2. b) Breakdown of proteins
3. c) Breakdown of lipids
4. d) Respiration

ANABOLISM

It is the synthesis reaction in which bigger molecule js formed from the smaller ones.

1. a) Synthesis of cellulose from glucose
2. b) Synthesis of starch and glycogen from glucose
3. c) Synthesis of fats and lipids
4. d) Synthesis of proteins

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LIVER

DETOXIFICATION

• The alcohol or any poisonous substance taken in the body is detoxified in the liver as liver contains enzymes for detoxification

BREAKDOWN OF BLOOD CELLS

• Old and work out blood cells are broken down in liver.

BREAKDOWN OF HARMFUL SUBSTANCES FOR EXCRETION

• Excess proteins is broken down into urea in the liver which is excreted by kidney as Urine

BREAK DOWN OF LACTIC ACID

• Lactic acid produced during anaerobic respiration in the muscles is transported into the liver via blood and liver converts it into carbon dioxide and water by taking in more oxygen which is inhaled as oxygen debt.

PHOTOSYNTHESIS VERSUS RESPIRATION

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Key Terms

Photosynthesis – It is the process by which green plants prepare their own food carbon dioxide and water are combined to form glucose and oxygen in presence of sunlight

Respiration – breakdown of food to release energy

Limiting Factors — Factor that limits the rate of photosynthesis

Endothermic Reaction— Reaction that takes in heat

Exothermic Reaction — Reaction that releases heat

Glucose — product of photosynthesis and fuel for respiration

Starch — Storage carbohydrate in plants

Glycogen — Storage carbohydrate in animals

Aerobic Respiration – Breaking down of food in presence of oxygen

Anaerboic Respiration – breaking down of food in absence of oxygen

Fermentation – Anaerobic respiration in plants that produces ethanol and carbon dioxide

Greenhouse – A glass or a plastic house to control the limiting factors and increase the rate of photosynthesis.

Metabolism – Sum Of all the catabolic and anabolic reactions of the body.

Liver – An organ involved in metabolism.

Lactic Acid — The product of anaerobic respiration in animals

Oxygen Debt —The extra oxygen needed exercise to break down lactic acid and recover to pre exercise state.

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Disclaimer:

I have tried my level best to cover the maximum of your specification. But this is not the alternative to the textbook. You should cover the specification or the textbook thoroughly. This is the quick revision to help you cover the gist of everything. In case you spot any errors then do let us know and we will rectify it.

References:

BBC Bitesize

Wikipedia

Wikimedia Commons

Image Source:

Wikipedia

Wikimedia

Commons

Flickr

Pixabay

Make sure you have watched the above videos and are familiar with the key definations before trying these questions. It is also good to time yourself while doing these questions so that you can work on the speed as well.

Using Food and Controlling Growth

• Respiration 1 MS
• Respiration 1 QP
• Respiration 2 MS
• Respiration 2 QP
• Respiration 3 MS
• Respiration 3 QP