Topic 6 - Plant Structures And Functions Flashcards
Where does photosynthesis take place ?
Photosynthesis takes place inside chloroplasts found in plants and algae
What type of reaction is photosynthesis?
The reaction is endothermic (needs energy)
What is the source of energy in photosynthesis ?
The source of this energy is sunlight
In photosynthesis How is sunlight trapped ?
sunlight is trapped by a chemical called chlorophyll inside chloroplasts
What is sunlight from photosynthesis used to make ?
It’s used to make carbohydrates
What are plants and algae know as and what stage of the food chain are they ?
Plants and algae are known as producers and form the first level of all food chains.
What is the word and symbol equation for photosynthesis ?
carbon dioxide + water → glucose + oxygen
6 CO2 + 6 H2O → C6H12O6 + 6 O2
(Over the arrow you can put light)
How does temperature effect the rate of photosynthesis?
Increasing the temperature increases the rate of photosynthesis because more energy is provided.
However, if the temperature is increased to above about 45°C (optimal temperature) , the enzymes that catalyse (speed-up) the reaction begin to denature (not work anymore).
This causes the rate of the reaction to drop sharply until it stops altogether.
How does light intensity effect the rate of photosynthesis ?
Increasing light intensity increases the rate of photosynthesis because more energy is provided.
However, if the light intensity is increased above a certain threshold, the rate of photosynthesis will not increase because another factor (such as temperature) is limiting the rate of the reaction.
How do carbon dioxide concentrations effect the rate of photosynthesis ?
Increasing the carbon dioxide concentration increases the rate of photosynthesis.
However, above a certain threshold, further increases in the carbon dioxide concentration do not increase the rate of photosynthesis because another factor (such as light intensity) is limiting the rate of reaction.
How does chlorophyll concentration effect the rate of photosynthesis ?
High chlorophyll concentration gives a high rate of photosynthesis
What are the limiting factors of photosynthesis ?
A limiting factor restricts the rate of a reaction. The identity of the limiting factor in photosynthesis depends on the conditions faced by the plant. (Winter) (Night) (Warm and bright) (Mineral deficient soli)
How is the winter a limiting factor for photosynthesis?
In winter, temperature is usually the limiting factor.
How is the night a limiting factor of photosynthesis ?
At night, light intensity is usually the limiting factor.
How is mineral-deficient soil a limiting factor of photosynthesis?
If plants are grown in mineral-deficient (lacking minerals) soil, they may not absorb enough minerals to produce lots of chlorophyll.
In this case, chlorophyll concentration can be the limiting factor
In warm and bright conditions what is the limiting factor of photosynthesis?
In warm and bright conditions, carbon dioxide concentration is usually the limiting factor.
How do you test for the rate of photosynthesis?
You can easily investigate the effect of light intensity on the rate of photosynthesis by using an aquatic (lives in water) plant like pondweed.
To do this, change the distance between the lamp and the pondweed and count the number of bubbles produced.
In this experiment, light intensity is the independent variable and the number of bubbles is the dependent variable.
What is the inverse square law ?
Light intensity = 1/distance ^2
What is the difference between accuracy, reliability, and validity?
Accuracy: Accuracy is how close a measured value is to its true value. For example, let’s say we have a 1 kg (1,000 g) bag of sugar. We then take this bag and place it on some scales. The scales say the bag of sugar weighs 1 kg, so we would say the scales are accurate.
If the scales said the bag of sugar weighed 750 g, the scales would be inaccurate.
Reliability: Reliability refers to the ability of an experiment to produce consistent results. For example, let’s say we weigh the same 1 kg bag of sugar on a different set of scales. On the first weigh, the scales say the sugar weighs 750.5 g. On the second weigh, the scales say the bag of sugar weighs 750.5 g.
These scales are reliable as they produce the same result each time.
However, they are not accurate as the bag of sugar actually weighs 1 kg (the scales are reliable but inaccurate).
Validity: Validity is how appropriate an experimental method is at achieving the aim of an experiment. For example, a valid method for measuring the weight of a bag of sugar is using a set of scales.
Using a thermometer to measure the weight of the bag of sugar would not be a valid experimental method (…surprisingly).
How are root hair cells specialised?
Root hair cells are specialised (to perform a specific function). Their structure allows the plant to absorb more water. They also allow a plant to take in the minerals it needs to survive
How is the root hair cell adapted to its function?
No chloroplasts - These cells are located underground. This means that they do not contain chloroplasts (there is no light for photosynthesis).
Long projections - Root hair cells have long projections that increase the surface area that the plant can use to absorb water and minerals.
How is the xylem cell specialised ?
The xylem is specialised to transport water up the stem of a plant and into the leaves.
How have xylem cells adapted to their function ?
Open ended cells - Xylem vessels are made up of a series of connected dead xylem cells.
The end walls of the dead cells are broken to allow water to move through.
Lignin - Lignin (a substance) strengthens the cell walls of xylem cells.
Why are xylem cells’ end walls broken ?
The end walls of the dead xylem cells are broken to allow water and dissolved minerals to move through.
What are stomata and what is their function ?
Stomata are gaps in the lower epidermis of leaves that facilitate (make easier) the diffusion of gases, including evaporated water, in and out of the leaf
What are guard cells and what are their functions ?
Cells that can open and close the stomata
What happens in the opening of stomata ?
The guard cells can open the stomata by taking up lots of water, causing them to swell.
What happens in the closing of the stomata ?
To close the stomata, the guard cells lose water and return to a limp state.
What does the state of stomata achieve ?
The state of stomata (open or closed) achieves a balance between allowing gases for photosynthesis into the leaves and conserving water in the plant.
When there is an abundance of water what is the state of stomata and why ?
OPEN:
When water is abundant (lots available) the plant can afford to lose water.
So it opens the stomata to allow gases for photosynthesis to move freely in and out of the leaf.
When there is scares water what is the state of stomata and why ?
CLOSED:
When water is scarce (rare), stomata close in order to prevent further water loss.
This is achieved by guard cells returning to a limp state after they lose water.
What is the state of stomata at night and why ?
CLOSED:
At night, stomata close because, in the absence of sunlight, carbon dioxide is not required for photosynthesis.
At this time, their only objective is to prevent water loss.
