B4: Bioenergetics Flashcards
What are the structures of the leaf and their purpose?
Waxy Cuticle - A waterproof layer on top of the leaf which prevents moisture being lost.
Epidermis - Acts as a barrier to the outside world
Palisade Mesophyll - Has a strong concentration of chlorophyll, and captures sunlights using chloroplasts for photosynthesis
Spongey Mesophyll - An area consisting of large empty gaps suitable for the diffusion of carbon dioxide & oxygen.
Phloem Vessels - Transport Glucose formed during photosynthesis away from the leaf.
Xylem Vessels - Transport water and Minerals up to the leaf from the root, so that it can be used in photosynthesis
Stomata - Gaps in the Lower Epidermis that allow the entry and exit of gas (and small loss of moisture)
Guard Cells - Cells on either side of the stomata that can open and close it.
What is the word equation and balanced equation of Photosynthesis?
Word Equation:
Water + Carbon Dioxide → Oxygen + Glucose
Balanced Equation:
6H₂O + 6CO₂ → 6O₂ + C₆H₁₂O₆
What are the primary organs of a plant and their functions?
The Stem: Supports the plant
The Leaves: The site of photosynthesis
The Roots: Absorbs moisture and Mineral ions
What type of reaction is photosynthesis and why?
Endothermic, as energy is being taken in from the sun
What is the experiment that proves the existence of photosynthesis, and its method?
Proof of Photosynthesis:
1. Place two plants under differing light conditions (One in intense light, the other in complete darkness)
2. Leave both plants for 10 minutes
3. Use an iodine to test for the presence of starch in each of them
↳ The one in the light should test positive (and turn black)
↳ The one in the dark should test negative (and show no change)
What are the Limiting factors of photosynthesis?
- The Intensity of Light
- The Concentration of CO₂ in the surrounding environment
- The Plant’s temperature
Note: The concentration of chlorophyll can also affect this
What do the Limiting factors of photosynthesis look like graphically?
CO₂: Gradual increase before plateauing
Light Intensity: Gradual increase before plateauing
Temperature: Has an optimum, at which it peaks. Beyond this optimum, enzymes denature and it falls to 0
What is the ruling for calculating Light Intensity?
The Inverse Square Law:
In words: for every time the distance doubles, the intensity of light quarters.
Formulaic: 1 ÷ distance²
How do plants use Glucose?
- They store it in a PERMANENT FORM, such as starch, fats or oils
- They combine it with NITRATE IONS to form AMINO ACIDS
- They use it to RESPIRE
- They use it to form CELLULOSE
What are the advantages of artificially farming?
- Maximise Crop Yield
- Maximise Profits
- Hard to control weather & conditions in an open field
Which conditions are controlled when artificially farming, and how is it done?
The controlled conditions are: LIGHT INTENSITY CO₂ CONCENTRATION TEMPERATURE MOISTURE LEVELS MINERAL ABUNDANCE
They are controlled using electricity and gas
What are Hydroponics?
Hydroponics are a way of farming that involves cultivating crops in mineral-rich water.
What are the advantages and disadvantages of Hydroponics?
Advantages:
- Crops are clean & soil-free
- No need to prepare land
- Less staff required
- Faster turnover
Disadvantages:
- Expensive
- Require constant monitoring
- Vulnerable to power outages
What is respiration?
A process that occurs within the cells of most organisms, which breaks down glucose to release energy. There are two types: aerobic and anaerobic
What type of reactions are aerobic and anaerobic respiration, and why?
Exothermic, as Glucose is being broken down to release energy.