Bioenergetics Flashcards
What are autotrophs?
Organisms that can make their own food using light, water, and carbon dioxide
Why are plants called producers in food chains?
Because they can make their own food through photosynthesis
What type of reaction is photosynthesis?
An endothermic reaction
Where does most photosynthesis take place in a plant?
In specialised mesophyll cells packed with chloroplasts
What is the function of chlorophyll in plants?
To absorb light energy for photosynthesis
What are the main products of photosynthesis?
Sugars used for making substances a plant needs and for respiration
List the reactants required for photosynthesis.
- Light
- Water
- Carbon dioxide
What factors affect the rate of photosynthesis?
- Light intensity
- Carbon dioxide concentration
- Temperature
- Amount of chlorophyll
How does temperature affect photosynthesis?
It affects the kinetic energy of particles, influencing the rate of collisions
What happens to enzymes at high temperatures during photosynthesis?
They can be denatured, reducing the overall rate of photosynthesis
What is the relationship between light intensity and photosynthesis rate?
More light increases the rate until another factor limits it
How does carbon dioxide concentration affect photosynthesis?
More carbon dioxide leads to a faster reaction rate until limited by another factor
What role do chloroplasts play in photosynthesis?
They contain chlorophyll, which absorbs light energy
What factors can affect the amount of chlorophyll in a plant?
- Diseases
- Lack of nutrients
- Loss of leaves
True or False: Water is considered a limiting factor in photosynthesis.
False
What is the inverse square law?
It shows the relationship between light intensity and distance
Fill in the blank: The equation for light intensity is _______.
1/d²
What is the aim of the investigation using an aquatic organism?
To investigate the effect of light intensity on the rate of photosynthesis
How can the rate of photosynthesis be measured in aquatic plants?
By measuring the volume of oxygen produced
What is one improvement for measuring gas produced in photosynthesis?
Use a gas syringe to collect the volume of gas produced
What are the main uses of glucose in plants?
- Used for respiration
- Converted to insoluble starch for storage
- Used to produce fat or oil
- Used to produce cellulose
- Combined with nitrate ions to produce amino acids
What reagent is used to test for starch in leaves?
Iodine solution
True or False: Plants only photosynthesize during the day.
True
What is cellular respiration?
An exothermic reaction continuously occurring in living cells
What does cellular respiration release?
Energy
What do organisms need energy for?
- Chemical reactions to build larger molecules from smaller molecules
- Muscle contraction to allow movement
- Keeping warm (to maintain a constant temperature suitable for enzyme activity)
What is aerobic respiration?
Respiration using oxygen to transfer energy from glucose
What is the word equation for aerobic respiration?
Glucose + Oxygen → Carbon Dioxide + Water + Energy
Where does aerobic respiration primarily occur?
In the mitochondria
What is anaerobic respiration in animals?
The incomplete breakdown of glucose into lactic acid without oxygen
When does anaerobic respiration occur?
When the body can’t supply enough oxygen for aerobic respiration, such as during vigorous exercise
What is the word equation for anaerobic respiration in animals?
Glucose → Lactic Acid + Energy
What is produced during anaerobic respiration in plants and yeast?
Ethanol and Carbon Dioxide
What is fermentation?
Anaerobic respiration in yeast cells
What is the economic importance of fermentation?
- Manufacture of bread (carbon dioxide makes dough rise)
- Production of alcoholic drinks (ethanol)
What are the key differences between aerobic and anaerobic respiration?
- Need for oxygen
- Differing products
- Relative amounts of energy transferred
True or False: Cellular respiration is the same as breathing.
False
What happens to muscle contractions during exercise?
They increase, leading to greater energy demand
How does the body respond to increased oxygen demand during exercise?
- Breathing rate increases
- Breath volume increases
- Heart rate increases
What is created when the body cannot supply sufficient oxygen during vigorous exercise?
An oxygen debt
What happens to lactic acid after vigorous exercise?
- It can be oxidised to form carbon dioxide and water
- It can be transported to the liver and converted back into glucose
What is metabolism?
The sum of all the reactions in a cell or the body
What role does energy play in metabolism?
It allows enzyme-controlled reactions to occur inside cells
What are the main metabolic reactions?
- Synthesis and breakdown of carbohydrates
- Synthesis and breakdown of lipids
- Synthesis and breakdown of proteins
What is the role of glucose in carbohydrate metabolism?
- Used in the synthesis of starch (energy storage in plants)
- Used in the synthesis of glycogen (energy storage in animals)
- Broken down during respiration to release energy
What is the role of glycerol in lipid metabolism?
Combined with three fatty acids to synthesize lipids for energy storage
How are amino acids produced?
From glucose and nitrates
What happens to excess proteins?
They are broken down to produce urea, which is excreted from the body
