Plants and Photosynthesis Flashcards
What minerals are needed for plant growth? How do they enter the plant?
5 marks
Minerals needed for plant growth include:
1. Nitrogen
2. Phosphorus
3. Potassium
4. Magnesium
All minerals enter the plant through the roots.
Define germination.
1 mark
Germination is the process by which a plant grows from a seed.
What three factors are required for germination?
3 marks
- Warmth
- Oxygen
- Sunlight
List and explain the parts of a flowering plant.
10 marks
Male
The stamen is the male sex organ.
1. Pollen grains are grown in the anther.
2. The filament holds up the anther.
Female
The carpel is the female sex organ.
1. The stigma is sticky to trap pollen grains.
2. The pollen on the stigma reaches the ovary via the style.
2. The ovary produces female gametes.
2. The female gamete is within the ovule.
Neither sex
2. Sepals protect the flower whin it is growing as a bud.
3. The nectaries produce a sugary solution called nectar. This is food that attracts some insects.
4. The bright colours in the petals attract insects.
Describe the stages of pollination, fertilisation and seed formation.
6 marks
- Pollination is the transfer of pollen from the anther to the stigma. Plants can be pollinated by animals, insects, water or wind.
- In each pollen grain is a male pollen nucleus. Inside each ovule is a female ovule nucleus. Once the pollen has landed on the stigma, it starts growing a tube down through the style to the ovary. The pollen nucleus travels down this tube to reach the ovule nucleus.
- After fertilisation, the ovule develops into a seed. Each seed contains a dormant embryo plant. The embryo has a food store. The ovary develops into a fruit around the seed.
Describe the various methods of seed dispersal.
8 marks
- Animals - the seed clings on to an animal’s fur.
- Wind - the seed is blown by the wind.
- Water - the seed floats away in a river of sea.
- Explosions - seeds are dispersed when lots of pressure is discharged at once.
Define photosynthesis and write a full word equation for the reaction. List the reactants and products.
3 marks
Photosynthesis is the process by which plants make food.
Reactants ====> Products
Carbon dioxide + water ====> glucose + oxygen
in the presence of sunlight and chlorophyll
What is chlorophyll, where is it found and what is its role in photosynthesis?
3 marks
- Chlorophyll is a pigment that gives plants their green color, and it helps plants create their own food through photosynthesis.
- It is found throughout the plant, but mostly in the palisade cells.
What is the role of light in the photosynthesis reaction?
1 mark
It provides the energy that a plant needs to make its own food.
Where does photosynthesis take place (which part of the plant, which cell organelle)?
2 marks
Photosynthesis takes place in the leaves of a plant, in the palisade cells.
List the parts of a leaf.
7 marks
- Waxy cuticle
- Vein
- Guard cell
- Stomata
- Epidermis
- Palisade cell
- Spongy mesophyll
State how the leaf is adapted to its function.
2 marks
It is broad and flat, so has lots of surface area for absorbsion of sunlight.
Describe the starch test.
10 marks
- Remove a healthy leaf from a tree/plant.
- Place the leaf in boiling water for at least 30 seconds. This kills the leaf and prevents further reactions.
- TURN OFF THE BUNSEN BURNER. Soak the leaf in a boiling tube (not a tube that is boiling) of ethanol until all the green pigment is removed from the leaf.
- Place the leaf back in the hot water to soften it since it will be stiff after the ethanol.
- Spread the leaf out on a white tile and put a few drops of iodine solution over its surface.
Result: The areas that contain starch will be stained blue/black by the iodine, and the places without starch will be orange/brown.
Apparatus: Bunsen burner, beaker of water, boiling tube of ethanol, tweezers, white tile, iodine solution
Safety notes: Make sure you TURN OFF THE BUNSEN BURNER WHILST THE ETHANOL IS IN USE because ethanol is highly flammable.
State and explain the limiting factors of photosynthesis.
8 marks
- Light intensity - more light = more photosynthesis
- Temperature - optimum is between 10°C and 25°C
- CO₂ levels - the more CO₂, the more photosynthesis
- Amount of chlorophyll - less chlorophyll = less photosynthesis
Describe an experiment to show the effect of light intensity on the rate of photosynthesis.
Apparatus
* Lamp
* Ruler
* Large beaker of water
* Test tube and funnel
* Pondweed (elodea)
* Thermometer
* Glass heat shield (beaker of water)
* Sodium hydrogen carbonate
* Stopwatch
Risk assessment
* Hot lamp - take care not to touch the lamp
Method
1. Set up the equipment as shown in the diagram, adding sodium hydrogen carbonate to t he beaker with the plant.
2. Place the lamp 50 cm away from the plant.
3. Count the number of bubbles produced in 1 minute. Repeat for a second minute.
4. Move the lamp 45 cm away, leave for 2 minutes, then count the number of bubbles produced in one minute. Repeat for a second minure. Repeat for a third minute.
5. Repeat step 4 for different distances: 40 cm, 35 cm, 30 cm, 25 cm, 20 cm or up until the point where the temperature alters.
6. Record results in a table and plot a graph.
