B5 - Plant Nutrition Flashcards
Define photosynthesis.
The process by which plants manufacture carbohydrates from raw materials using energy from sunlight.
What is the word equation for photosynthesis?
carbon dioxide + water -> glucose + oxygen
State the balanced equation for photosynthesis.
6CO2 + 6H20 –light/chlorophyll–> C6H12O6 + 6O2
What is the role of glucose?
used in respiration
What is the role of sucrose?
stored in fruit and nectar to attract insects for pollination
What is the role of starch?
food store in chloroplasts OR energy
What is the role of cellulose?
to form strong cell walls
What is the role of fats and oils?
foot store and growth
What is the role of proteins?
growth and repair
List the five main ways plants use glucose.
- For respiration
- Making cellulose
- Making amino acids
- Stored as fat or oils
- Stored as starch
What is an energy transducer?
Organelles that can transform one source of energy into another.
Name an energy transducer.
Chloroplasts.
What is the pigment that absorbs light energy?
Chlorophyll.
What is the role of chloroplasts?
To act as energy transducers, converting light energy into chemical energy.
Where does photosynthesis happen? [2]
The leaves of the plant. Specifically, chloroplasts.
What does autotrophic mean?
Self-feeding.
How do you test a leaf for starch? [4]
1) Hold the leaf in boiling water with tweezers. This stops any chemical reactions happening inside the leaf and also breaks down cell walls.
2) Put the leaf in a boiling tube with some ethanol and put it in an electric water-bath until it boils. This gets rid of any chlorophyll and makes the leaf an almost white colour.
3) Dip the leaf in warm water to soften the brittle leaf and allow penetration by iodine solution.
4) Place the leaf on a white tile and add a few drops of iodine solution. If starch is present the leaf will turn blue-black.
What is a variegated leaf?
A leaf that has different colors. E.g. green (chlorophyll) and white (no chlorophyll)
List the chemical elements in a carbohydrate.
Carbon, Hydrogen, Oxygen.
What is the test for starch?
Iodine solution. If starch is present it will turn blue-black.
Where are most of the chloroplasts found in the leaf?
The palisade mesophyll layer.
What are the holes that allow diffusion of carbon-dioxide and oxygen in and out of the leaf called?
Stomata. They are mainly present in the lower epidermis. They close in the dark.
What is the top layer of the leaf and what is its function?
The waxy cuticle. It reduces water loss.
What is the layer under the waxy cuticle and what is its function?
The upper epidermis. It is usually one cell thick and transparent to allow free passafe of light. It prevents the entry of disease-causing organisms such as bacteria and fungi.
What is the layer where the chloroplasts are?
Palisade Mesophyll. Tall, thin cells arranged in columns and separated by narrow air spaces. Contain many chloroplasts and dense packing of cells ensures maximum absoption of light energy.
What is the vein in the plant?
Transport system that contains xylem and phloem. Xylem is on top.
What layer is the vein found in?
Spongy Mesophyll. Loosely packed cells covered in a thin layer of water. Lots of air space enable diffusion of gases through the leaf. Air spaces are saturated with water so water diffuses out the leaf.
What happens to the guard cells when the plant has plenty of water?
They become turgid and swell causing the cell wall to curve and open the stomata.
Name the two mineral ions that plants need.
Nitrate ions and Magnesium ions.
What are nitrate ions needed for?
Making amino acids and proteins, which are needed for cell growth.
What happens if a plant has a nitrate ion deficiency?
It will be stunted and older leaves will turn yellow.
What are magnesium ions needed for?
Needed to make chlorophyll.
What happens if a plant has a magnesium ion deficiency?
It won’t make enough chlorophyll and will have chlorosis (the leaves of the plant will turn yellow). Also have stunted growth.
Where do minerals enter a plant?
Through the root hair cells.
Define limiting factor.
Something present in the environment in such short supply that it restricts life processes.
Name three limiting factors that affect photosynthesis.
Light intensity
Temperature
CO2 concentration
How does light intensity affect photosynthesis?
Increases light intensity increases the rate of photosynthesis up to a certain point where it will level off.
How does temperature affect photosynthesis?
Optimum temp. Like enzymes if it gets to high the enzymes will denature and the rate of photosynthesis will decrease.
What five things do you need to include when planning an investigation?
Independent variable
Dependent variable
Control variables
Reliability
Safety
