4. Bioenergetics Flashcards
What is respiration?
Releasing energy from glucose
Word equation for aerobic respiration?
Oxygen + Glucose -> Carbon Dioxide + Water + (energy)
Balanced symbol equation for aerobic respiration?
6O2 + C6H12O6 -> 6CO2 + 6H2O
Where does aerobic respiration take place?
In every living cell on specialised membranes
Is aerobic respiration exothermic?
Yes
What does exothermic mean?
Gives out heat
Where are specialised membranes for aerobic respiration in eukaryotes?
In mitochondria
Where are specialised membranes for aerobic respiration in prokaryotes?
In mesosomes
What is the role of cytoplasm in aerobic respiration?
- Where enzymes are made
- Location of reaction in respiration
What is the role of the nucleus in aerobic respiration?
Hold genetic code for enzymes involved in respiration
What is the role of mitochondria in aerobic respiration?
Contain enzymes for aerobic respiration
What is the role of the cell membrane in aerobic respiration?
- Allows gases and water to pass in and out of cell
- Controls passage of other molecules
What happens to oxygen in respiration?
Breathed in through lungs -> circulated in blood -> diffuses to cells
What happens to glucose in respiration?
Digested in digestive system -> absorbed in blood -> diffuses into cells
What happens to carbon dioxide in respiration?
Produced by respiration in cells -> diffuses into blood -> circulates in the blood to the alveoli -> diffuses into lungs through alveoli -> breathed out
What happens to water in respiration?
Produced by cells in respiration-> moves out of cells by osmosis -> circulates in blood -> excess removed through sweat, urine etc
What is energy released in aerobic respiration used for?
- contraction of muscles
- active transport
- chemical reactions
- cell division
- protein synthesis
Where are mitochondria found?
In all plant and animal cells as well as in fungi and algals cells
Adaptations of mitochondria for respiration?
Folded inner membrane = larger SA for enzymes involved in aerobic respiration
What does the number of mitochondria in a cell show?
How active the cell is
What does having a greater muscle mass mean?
You will need more energy
Why do boys need more energy than girls?
Boys have more muscle cells and therefore more mitochondria to release energy
What are mitochondria?
Organelles which carry out aerobic respiration to release energy from glucose for use in the cellg
Why do muscles use a lot of energy?
For movement and support, as well as life processed such as breathing and circulation
What is muscle tissue made of?
Protein fibres that occur in big groups called muscles
How do muscles cause movement?
They contract
What do muscles do when their role is finished?
Relax
What do muscles contain?
Many mitochondria and glycogen stores
How do muscles contract?
Using energy from respiration
What is glycogen?
A carbohydrate that is rapidly hydrolysed into glucose
What does hydrolysed mean?
Split using water
Why does a person’s heart and breathing rate increase after exercise?
When someone is exercising they need more energy released by respiration so the heart pumps harder to carry oxygen and glucose and remove carbon dioxide
Word equation for photosynthesis?
Carbon dioxide + Water -> Glucose + Oxygen
Symbol equation for photosynthesis?
6CO2 + 6H2O -> C6H12O6 + 6O2
What are the reactants in photosynthesis?
Carbon dioxide and water
What are the products of photosynthesis?
Oxygen and glucose
How does carbon dioxide become available for photosynthesis?
It diffuses in from the air through the stomata of the leaf
How does water become available for photosynthesis?
From the soil it is absorbed by the root hair cells (large SA) by osmosis
What is glucose produced by photosynthesis used for?
Used in respiration, converted into starch, used to produce fat oil for storage, cellulose, and protein synthesis
What is oxygen produced by photosynthesis used for?
Some used in respiration - oxygen diffuses out of the leaf through stomata
How is a leaf adapted for photosynthesis?
- Flat and thin, large SA to absorb maximum light energy
- contains chlorophyll
- network of veins to transport water and minerals to leaf and carbohydrates away
- waxy layer is translucent to light can pass through to palisades
Why are leaves so thin?
So gases (CO2) can diffuse to the palisade cells quickly
How to test for starch?
Iodine
Colour change in iodine when starch is present?
yellow/brown -> blue/black
How does light intensity affect the rate of photosynthesis?
As light intensity increases, the rate of photosynthesis increases
In what proportion do light intensity and distance increase?
light intensity decreases to the square of the distance - inversely proportional
light intensity (IS PROPORTIONAL TO) 1/d2
Light intensity when a lamp is 10cm from the pondweed?
light intensity = 1/100 = 0.01 a.u.
Light intensity when a lamp is 30 cm from the pondweed?
light intensity = 1/30 squared = 0.001 a.u. (1 s.f.)
What are the limiting factors of photosynthesis?
Carbon dioxide, light intensity and temperature
What are limiting factors of photosynthesis when light intensity is increased?
Carbon dioxide and temperature
What are limiting factors of photosynthesis when temperature is increased?
photosynthetic enzymes denatured at 45 degrees celsius
What are limiting factors of photosynthesis when carbon dioxide is increased?
light or temperature - CO2 no longer affects the rate
What is hydroponics?
A growing system that uses water instead of soil
Positives of hydroponics?
- quicker growth rate
- no herbicides/pesticides
- use of fertiliser contained -> less harmful to environment
- monitor & manipulate oxygen and minerals
Negatives of hydroponics?
- more workers = more costly
- labour intensive
- expensive monitoring systems
- expensive to start business (green house etc.)
What is small holding?
Small farms meant crop rotation was required so crops weren’t grown on some fields for land to recover
What is arable farming?
Farming a larger area of land: after harvest stubble is ploughed back into land and fertiliser added to maintain mineral levels
How does the body react to increased demand for energy during exercise?
- increase in heart & breathing rate, breath volume
- glycogen stores in muscles -> glucose
- flow of oxygenated blood increases
What do the body’s responses to exercise increase?
Rate of supply of glucose and oxygen to muscles, and rate of removal of CO2 from muscles
What does the body respond to during exercise?
The increased demand for energy
Why do muscles contain a glycogen store but most other tissues don’t?
Normal cells obtain glucose by diffusion and muscles work hard therefore need more energy
What is anaerobic respiration?
Respiration without oxygen
Why does anaerobic respiration occur?
During exercise muscle cells may become short of oxygen and it cannot be supplied fast enough
Energy can still be obtained from glucose without use of oxygen
Word equation for anaerobic respiration?
Glucose-> lactic acid + energy (small amounts)
What is muscle fatigue?
When muscle fibres become fatigued after carrying out vigorous exercise
What happens when cells are respiring without oxygen?
- Not efficient as aerobic
- Oxidation of glucose molecules incomplete
- Less energy released
What is oxygen debt?
When lactic acid has to be broken down after exercise which needs oxygen
Word equation for oxygen debt?
Lactic acid + oxygen -> carbon dioxide + water
What happens as lactic acid accumulates inside the muscle cells?
Enters bloodstream
What happens to circulating lactate in the blood?
The liver soaks it up
What does the liver do to lactate that it soaks up?
Oxidises lactic acid to pyruvate
What enzyme helps oxidise lactic acid to pyruvate?
Lactate dehydrogenase
What does lactate dehydrogenase do?
Uses electrons from lactate to reduce NAO to NAOH
What happens to pyruvate?
Enters mitochondria via transporter, where it may meet with a couple of fates
Why do heart and breathing rate stay high until oxygen debt is paid off?
To supply the extra oxygen
How do arteries supplying the leg muscles alter the rate of blood flow through them during exercise?
They dilate so more blood can flow, meaning it can reach different areas of the body more quickly
How does an increase in heart rate help during exercise?
Muscles use more energy so more oxygen and glucose were supplied to part of the body meaning that more carbon divide and lactic acid were removed
What is metabolism?
The sum of all the reactions in a cell or the body
What is energy transferred by respiration used for in terms of metabolism?
Energy is used by the organism for continual process of metabolism that synthesise new materials
What are the types of metabolism?
Where larger molecules are made from smaller ones and others where larger molecules are broken down into smaller ones
Examples of chemical reactions where larger molecules are made of smaller ones?
- Small glucose molecules -> stark, glycogen and cellulose
- Lipids -> 1 molecule glycerol and 3 of fatty acids
- Glucose + nitrate ions -> amino acid
Examples of chemical reactions where larger molecules broken into smaller ones?
- Glucose broken down in respiration (releases energy)
* Excess protein broken down -> urea
Types of metabolic pathways?
Anabolic and catabolic
What is an anabolic pathway?
Requires energy - used to build up large molecules from smaller ones
What is a catabolic pathway?
Releases energy - used to break down large molecules into smaller ones
Does an anabolic pathway release or require energy?
Requires energy
Does a catabolic pathway release or require energy?
Releases energy
Which metabolic pathway breaks down molecules?
Catabolic
Which metabolic pathway builds up molecules?
Anabolic
Example of where anabolic pathways are used?
Photosynthesis - where glucose molecules are formed from different raw materials (carbon dioxide and water)
Examples of where catabolic pathways are used?
Food digestion - where different enzymes break down food particles so they can be absorbed by the small intestine
Are almost all metabolic reactions reversible?
Yes
What happens if an enzyme of substrate is unavailable in a metabolic pathway?
The product may be made using an alternative route; another metabolic pathway
How does water produced by respiration leave cells?
By osmosis
