Reproduction in plants Flashcards
What does the sepal do?
Protects the unopened flower
What do the petals do?
They are brightly colored in insect-pollenated plants to attract insects
What does the anther do?
Produces and releases the male sex hormone (Pollen grain)
What does the stigma do?
Top of the female part of the flower which collects pollen grains
What does the ovary do?
Produces the female sex hormone (Ovum)
What is pollenation?
When pollen is transferred from the anthers to the stigma
What is cross polination?
When pollen is transferred from a different flower
What is self pollination?
When pollen is transferred from the same flower
What is an insect pollenated plant?
When the pollen is transferred by insects (Or sometimes animals e.g. Bats or birds)
What is a wind pollentated plant?
When pollen is transferred by the wind
How do insects pollenate plants?
When insects enter a flower, they search for the nectar at the bottom. As they get that nectar, the insect’s body might brush against the anthers. When the insect visits a new plant they might brush against the stigma and therefore pollenate the plant.
How do the petals adapt to insect pollenation
They are large and bright to attract insects
How does the scent and nectar adapt to insect pollenation
They are present. The nectar and scent attract insects into the plant and push past the stamen to get the nectar
How does the number of pollen grains adapt to insect pollenation
They are in moderate amounts. Insects transfer pollen grains efficiently with a high chance of successful pollenation
How do the pollen grains adapt to insect pollenation
They are larger and sticky or spiky to attach to insects and be carried away
How do the anthers adapt to insect pollenation
They are inside the flower, stiff and firmly attached to brush against insects
How does the stigma adapt to insect pollenation
They are inside the flower and sticky, so pollen grains stick to it when the insect goes past
How does wind pollenation work?
When ripe, the anthers open and shed their pollen into the air. The wind then blows this pollen until it lands on the stigma of a plant of the same species. Resulting in pollenation.
How do the petals adapt to wind pollenation?
They are small and dull, often green or brown in colour
How do the scent and nectar adapt to wind pollenation?
No scent. They don’t need to waste unnecessary energy on making a scent if they don’t need to attract insects
How do the number of pollen grains adapt to wind pollenation
They are in large amounts. The more pollen there is the higher chance of pollination as most pollen grains are not transferred to another flower.
How do the pollen grains adapt to wind pollenation
They are smooth and small to float in the wind
How do the anthers adapt to wind pollenation
They are outside the flower and on loose filaments to release pollen grains easily
How do the stigma adapt to wind pollenation
They are outside the flower and feathery to catch drifting pollen grains
Describe how fertilisation and fruit formation happens:
- A pollen grain lands on the stigma and the pollen tube starts growing down into the style
-The pollen tube then enters the ovule through the micropyle - The pollen nucleus travels into the micropyle through the pollen tube and therefore fuses with the ovum nucleus resulting in fertilization
-The ovary will develop into a fruit and the ovule develops into a seed
What are the 3 key factors needed for seed germination?
Water- Swells the seed, breaks the seed coat, and activates enzymes for growth
Oxygen -Necessary for respiration to provide energy
Warmth- Boosts enzyme activity and improves germination until a certain temperature
What is the apparatus needed to investigate the conditions of germination?
Test tubes
Test tube holder
Cress seeds
Cotton wool
Fridge
What is the method for investigating the conditions of germination?
-Prepare 4 test tubes with 10 cress seeds on cotton wool label them a b c d
-Tube A: Dry cotton wool
- Tube B: Moist cotton wool
- Tube C: Cover the seeds and wool in water and a layer of oil
- Tube D: Moist cotton wool that gets left in a fridge
- Tubes ABC will be kept in room temp
Compare the amount of germinated seeds in each tube
What are the results going to be from the investigation of conditions of germination?
Test tube A: Dry cotton wool- NO seeds germinated
Test tube B: Moist cotton wool- Seeds germinated
Test tube C: Water and a layer of oil- NO seeds germinated
Test tube D: Fridge- NO seeds germinated
What is meant by the term germination?
The beginning of seed growth
What do Cotyledons do?
They surround the embryo, storing food for the seedling. They also provide energy until the plant can photosynthesize
What is meant by the term Runner?
Horizontal stems with small plantlets that grow sideways out of the parent plant. Once they hit the soil these plantlets will grow and become independent from the parent plant
What is the method for cuttings?
-Gardeners take cuttings from good parents plants
- A section of the parent plant with a new bud is cut off
- This new cutting can be either placed into the water until new roots grow or directly into the soil
- Sometimes stems can be put into “rooting powder” which contains plant growth regulators that encourage new growth
- These cuttings will be genetically identical to the parent plant
