Inputs & Outputs
This gas is released by plants during photosynthesis and is essential for humans to breathe
What is Oxygen?
This green pigment in plant cells absorbs light energy for photosynthesis
What is chlorophyll?
If you move a plant from a sunny windowsill into a dark cabinet/cupboard, what happens to the rate of photosynthesis?
What is it decreases/stops?
A student wants to prove that plants need light to grow. She has two identical plants, two pots of soil, water, and a dark cupboard/cabinet. Describe the simplest possible experiment.
What is: put one plant in sunlight and one in the dark cupboard. Give both the same amount of water. Observe both plants over several days. The plant in the dark will stop growing and eventually die.
This vast South American forest is sometimes called the lungs of the Earth because it produces so much oxygen through photosynthesis.
What is the Amazon rainforest?
These are the 3 ingredients a plant needs to carry out photosynthesis
What are water, carbon dioxide (CO2), and light energy?
This tiny structure inside plant cells is where photosynthesis actually takes place
What is chloroplast?
These are 3 factors that can limit the rate of photosynthesis (make it slower)
what are light intensity, carbon dioxide (CO2) concentration, and temperature?
A scientist wants to measure the rate of photosynthesis in an aquatic plant. She counts something that the plant produces during photosynthesis. What does she count and how does she make the experiment faster or slower?
What is: she counts oxygen bubbles produced per minute by the aquatic plant. She can make it faster by increasing light intensity or adding more carbon dioxide (CO2). She can slow it down by moving the lamp further away or reducing temperature.
Coal, oil, and natural gas are called fossil fuels. Why do they contain energy? (and are therefore related to photosynthesis)
What is fossil fuels are the remains of ancient plants and organisms that captured energy from the Sun through photosynthesis millions of years ago.
Photosynthesis produces glucose. Name 2 things a plant does with that glucose
What are: use it for energy through respiration, convert it to starch for storage, use it to build cell walls as cellulose, use it to make proteins with soil minerals, etc etc 😊
These tiny pore found mainly on the underside of leaves allow carbon dioxide (CO2) to enter and oxygen to exit the leaf
What are stomata? (singular: stoma)
Why do some greenhouse farmers pump extra carbon dioxide (CO2) into their greenhouses ?
What is to increase the rate of photosynthesis and grow plants faster/produce more food?
Design a fair test to investigate whether light colour affects the rate of photosynthesis. What equipment do you need, what do you change, what do you measure, and what do you keep the same?
What is: Equipment: aquatic plant, coloured filters or coloured lights, timer, measuring cylinder or way to count bubbles. Change (independent variable): colour of light (red, blue, green, white). Measure (dependent variable): number of oxygen bubbles per minute OR volume of oxygen produced. Keep the same: distance from light, temperature, CO₂ concentration, same plant, same duration.
This organism, found in the ocean, produces approximately 50% of all the oxygen on Earth, more than all the world's forests combined.
What is phytoplankton/algae?
Note: Half the air you breathe came from tiny organisms in the ocean you've never seen. Why do you think ocean pollution is so dangerous?
At night plants cannot photosynthesis but they still need energy. What is the process they use instead? (This process is used by all animals)
What is respiration?
This vascular tissue transports water from the roots up to the leaves, and this OTHER vascular tissue transports glucose from the leaves down to the rest of the plant. Name both!
What are xylem (water up) and phloem (glucose down)?
Photosynthesis rate increases as temperature rises, but only up to a point. Above approximately what temperature does photosynthesis drops sharply? Explain why.
What is approximately 40°C, because above this temperature the enzymes/proteins involved in photosynthesis denature (change shape and stop working)?
A student claims that plants kept in a room with lots of people photosynthesize faster than plants in an empty room. Design an experiment to test this claim. What is the student's hypothesis and why might it be true?
What is: Hypothesis:plants in rooms with more people photosynthesize at a higher rate. Why it might be true:humans exhale CO₂ which increases CO₂ concentration in the air, providing more raw material for photosynthesis. Experiment:two identical rooms, same light levels, same temperature. One room with several people present, one empty. Measure oxygen production or CO₂ consumption of identical plants in each room over the same time period. Control variables: light, temperature, plant size, time of day.
As humans burn fossil fuels, carbon dioxide (CO2) levels in the atmosphere rise. Using your knowledge of photosynthesis, explain ONE way this might help plants and ONE way it might harm them.
What is: Might help: higher CO₂ concentration could increase photosynthesis rate (up to a point). Might harm: rising CO₂ causes global warming → higher temperatures → above 40°C enzymes denature and photosynthesis drops. Also causes drought → plants close stomata → CO₂ can't enter → photosynthesis stops.
What is carbon dioxide (CO2) + water + light --> glucose + oxygen
Leaves are perfectly designed for photosynthesis. Name 3 structural features of a leaf that make it good at photosynthesis and explain each
What are: Broad and flat → maximum surface area to absorb light; Thin → short distance for CO₂ to diffuse to cells; Transparent upper layer → lets light through to chloroplasts; Many chloroplasts → maximum photosynthesis; Network of veins → delivers water and removes glucose efficiently; Stomata on underside → gas exchange without losing too much water; Etc etc 😊
A plant is given plenty of water and carbon dioxide (CO2) but is kept at a constant dim light level. A student increases the carbon dioxide (CO2) concentration dramatically but the photosynthesis rate does not increase. Explain why
What is even with more carbon dioxide (CO2) available, the plant cannot photosynthesize faster because there is not enough light energy to drive the reaction. (limiting factor is the light, the factor in shortest supply controls the overall rate)
A student sets up a sealed glass jar with a plant inside and leaves it on a sunny windowsill. Three months later the plant is still alive and healthy despite never being watered or having fresh air added. Explain fully why the plant survived, naming all the processes involved.
What is: The plant photosynthesizes using light from the window. The plant also respires, consuming oxygen and producing CO₂ and water vapour. The CO₂ from respiration feeds back into photosynthesis and the gases cycle within the jar. Water vapour from respiration and transpiration condenses on the glass and runs back down to the soil so the water cycles within the jar.
Deforestation (cutting down forests) is considered one of the most serious environmental problems on Earth. Using your knowledge of photosynthesis AND respiration, explain THREE specific reasons why losing forests is dangerous for the planet.
What is any three of: Less photosynthesis → less CO₂ removed from atmosphere → accelerates climate change. Less oxygen produced. Loss of habitat destroys food chains that depend on plant glucose as the entry point of all energy. Soil erosion without roots → less water absorbed → changes local rainfall patterns → affects agriculture. Reduced transpiration from trees → less water vapour → less rainfall → desertification