SB6a-e Flashcards
(separated for semester 1 test 1)
What is the word equation of photosynthesis?
Carbon dioxide + water –> glucose + oxygen
What is an endothermic reaction?
When energy from the surroundings is taken in.
Where are the products of photosynthesis used?
They are used in respiration.
Glucose that isn’t used in respiration is stored as starch in the chloroplasts.
Oxygen is released into the atmosphere so that both plants and animals use it in respiration.
What are other products of photosynthesis that come from glucose?
- Sucrose
- Cellulose
- Lipids
- Proteins
What is biomass?
The dry mass of living organisms (g/m²).
How do we measure biomass?
All the water has to be removed in order to measure biomass. It cannot be done in animals because they will die, but can be done in plants. Measure the mass of the plant and put the plants into an oven to remove water by evaporation. Remove them from oven and measure mass then put them in the oven again for some time. If there is no further change in mass after removing the plants and weighing them again then all the water has evaporated.
Why do plants contain lots of chloroplasts and where do they store them?
Leaves contain lots of chloroplasts for photosynthesis and most of them are found inside the palisade cells. This is because palisade cells are found at the upper part of the leaves so that they can absorb as much sunlight as possible to carry out photosynthesis.
Check book page 125 and/or teacher note sheet.
What are stomata and where are they found?
Stomata are pores that open and close according to different conditions and are found at the lower part of the leaves. All stomata are open during the day and most are closed during the night.
What are stomata used for?
They allow oxygen, carbon dioxide and water vapour to enter and leave the leaf by diffusion.
Describe the function and structure of the stoma.
Made up of two guard cells that open and close when needed. Concentration of water in the guard cells determine whether the stomata will open or close. High concentration in the guard cells cause them to become swollen and rigid, making the stoma open. Low concentration in the guard cells cause them to shrink, making the stoma close.
Check book page 125 and/or teacher note sheet.
What is a limiting factor?
Any factor that can affect the rate of a reaction, usually by decreasing it.
What are the limiting factors affecting photosynthesis?
- Sunlight/light intensity
- Temperature
- Carbon dioxide concentration
- Water available
Explain the logic behind the sloping part and stable part of a sunlight limiting factor graph.
Sloping part: Sunlight is a limiting factor because any change in the sunlight intensity can change the rate of photosynthesis.
Stable part: Sunlight is no longer a limiting factor since a change in sunlight intensity will not affect the rate of photosynthesis. However, the rate levels off and remains constant, meaning another factor (e.g. C02 concentration, water, temperature) becomes limiting and does not allow the rate to increase any further.
Check book page 126 and teacher note sheet.
What is diffusion?
Movement of any particle/molecule from a region of high concentration to a region of low concentration (or down the concentration gradient).
What is osmosis?
Movement of water molecules ONLY from a region of high concentration to a region of low concentration through a partially permeable membrane.
What is active transport?
Movement of molecules from a region of low concentration to a region of high concentration (or up the concentration gradient) with the help of energy e.g. ATP (adenosine triphosphate).
What is the pathway of water and mineral ions from the soil up to the leaves?
Check book page 131 and teacher note sheet.
What ions do plants need and why?
Nitrates are used to help the plant remain healthy and grow, as well as making proteins and DNA.
What are the adaptations of roots and what is their purpose?
Have root hair cells which provide a large surface area and have very thin walls so that water and mineral ions can be absorbed very quickly.
How does water enter and leave the plant?
Moves into the root hair cells and into the xylem by osmosis. Moves up the stem and then to the leaves by capillary action.
Water is lost from the leaves by transpiration and evaporates into the atmosphere by diffusion through the stomata.
How do mineral ions enter and traverse through the plant?
The mineral ions dissolve in the water and move along with the water through the xylem from the roots up to the leaves.
How does glucose enter and traverse through the plant?
Glucose is converted into sucrose, then dissolves in the water and moves by translocation through the phloem tube.
What are the two tubes in plants and what do they do?
The xylem transfers water and mineral ions from the soil.
The phloem transfers sucrose from the site of production (leaves) to the rest of the plant.
Describe the characteristics and purpose of xylem vessels. (5)
- Long dead hollow tubes
- Wall of xylem made up of lignin which provides strength and support
- Transfers mineral ions and water
- There are pits on the wall used for water to move sideways
- Unbreakable chain of water inside the vessels due to weak forces of attraction (hydrogen bonds) between water molecules
Check book page 133 and diagram in notebook.
Describe the characteristics and purpose of the phloem. (5)
- Made of continuous sieve tubes, each of which is made up from a chain of sieve tube elements
- End walls of phloem sieve tube elements have holes in them enabling one cell to communicate with the other so sucrose moves through them
- These perforated end walls are called sieve plates and are alive cells when matured but without a nucleus
- Next to each sieve tube element there is a companion cells that contain mitochondria to do respiration and provide energy to the sieve tube
- Phloem is used for transport of sugars, amino acids, and other organic molecules produced as a result of photosynthesis
Check book page 133 and diagram in notebook.
What is translocation?
Movement of sucrose through the sieve tubes in the phloem around the plant.
What is transpiration?
Loss of water through the plant by evaporation.
How can we measure the transpiration rate of a plant?
Using a potometer.
What are the factors affecting transpiration?
- Temperature
- Wind
- Light intensity
- Humidity
How does temperature affect the rate of transpiration?
High temperature increases the rate - low temperature decreases the rate.
The higher the temperature, the more the water molecules gain kinetic energy, move faster and diffuse faster outside the leaf and through the stomata.
How does wind affect the rate of transpiration?
High wind increases the rate - low wind decreases the rate.
The more the wind, the more the water molecules will move away and create a concentration gradient, allowing the water to evaporate faster through the stomata.
How does light intensity affect the rate of transpiration?
High light intensity increases the rate - low light intensity decreases the rate.
The higher the light intensity, the wider the stomata so that they can absorb enough carbon dioxide for photosynthesis and to release oxygen into the atmosphere.
How does humidity affect the rate of transpiration?
High humidity decreases the rate - low humidity increases the rate.
Low humidity causes less water vapour in the atmosphere than inside the leaves creating a concentration gradient, so water will move outside by diffusion faster.
What are 4 more adaptations of leaves and what is their use?
Spongy mesophyll: allows gaps between the cells so that gases (oxygen, carbon dioxide, water vapour) can diffuse in and out of the leaves easily.
Network of xylem vessels: transport water for photosynthesis.
Epidermis cells: Hold the leaves together and protect the cells inside the leaves.
Cuticle: Waterproof and waxy in order to stop any water loss, water gained and microorganisms from getting into the leaves.
Check book page 134 for leaf structure.
What extreme adaptation do deciduous trees have and why?
Deciduous trees lose their leaves so that they wont lose water during extreme weather conditions.
What extreme adaptation do conifers have and why?
Conifers have needle-shaped leaves since they live up in the mountains where there is lots of wind. These leaves have less surface area so less water is lost through wind and snow will not be able to collect on them and damage them. They also have stomata in pits so that they are less exposed to the wind and less water is lost.
