Photosynthesis

Question 1

What is photosynthesis?

Answer 1

Photosynthesis is the process by which green plants use sunlight to convert carbon dioxide and water into glucose and oxygen.

Question 2

Where does photosynthesis take place in a plant?

Answer 2

It takes place in the chloroplast of plant cells, mainly in the leaves which contains chlorophyll which absorbs energy from sunlight.

Question 3

What are the products of photosynthesis?

Answer 3

Oxygen - released into the air
and
Glucose- a sugar used for energy or stored

Question 4

What is the equation for photosynthesis ?

Answer 4

Sunlight
Carbon + water ——> Glucose + Oxygen
Dioxide Chlorophyll

                  Sunlight

6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂

               Chlorophyll

Question 5

What are the 2 stages of photosynthesis?

Answer 5

1) The light dependent stage
Here is where the chlorophyll in the chloroplast traps light energy from the sun. The energy is used to split water (H2O) into Hydrogen (H) and Oxygen (O2). Oxygen is a waste product and diffuses out of the leaf. Energy is also stored in ATP

2) The light independent stage
Using energy from ATP, The hydrogen (H) from the above is combined with Carbon dioxide (CO2) to form glucose (C6H12O6).

Question 6

Which pigment is primarily responsible for capturing light energy in plants?

Answer 6

Chlorophyll

Question 7

What gas is taken in by plants during photosynthesis?

Answer 7

Carbon Dioxide

Question 8

What is the primary function of water in photosynthesis?

Answer 8

Water provides electrons and protons for the light-dependent reactions and produces oxygen as a byproduct.

Question 9

Fill in the blank: Photosynthesis primarily occurs in _____ leaves.

Answer 9

green

Question 10

What is the significance of photosynthesis to life on Earth?

Answer 10

Photosynthesis is crucial because it produces oxygen for breathing and organic compounds that are essential for most life forms on Earth. Also forms the base of the food chain.

Question 11

What is the end product of the light independent stage?

Answer 11

The end product is glucose.

Question 12

What is the effect of increasing temperature on the rate of photosynthesis?

Answer 12

Increasing temperature generally increases the rate of photosynthesis up to a certain point, after which it may decrease due to enzyme denaturation.

Question 13

What is the function of the stomata in plants?

Answer 13

Stomata are small openings on the surface of leaves that allow for gas exchange, including the intake of carbon dioxide and the release of oxygen.

Question 14

Fill in the blank: The light-dependent reactions convert _____ energy into chemical energy.

Answer 14

light

Question 15

Through which part of the leaf does carbon dioxide enter?

Answer 15

Stomata

Question 16

How does water reach the leaf cells?

Answer 16

Water is absorbed by roots, moves through the xylem, and enters leaf cells by osmosis.

Question 17

What happens to the glucose produced in photosynthesis?

Answer 17

Used in respiration for energy

Stored as starch
Converted to sucrose and transported

Used to build fats, proteins, and other carbohydrates

converted into cellulose or other organic compounds.

Question 18

How can farmers increase the rate of photosynthesis in crops?

Answer 18

By providing more light, increasing carbon dioxide levels, and controlling temperature in greenhouses.

Question 19

What test is used to prove that photosynthesis occurred?

Answer 19

The starch test: using iodine to test for the presence of starch in leaves.

Question 20

Why must a leaf be boiled in alcohol before testing for starch?

Answer 20

To remove chlorophyll and make the leaf pale so the color change with iodine can be seen.

Question 21

What are the main parts of a leaf involved in photosynthesis?

Answer 21

Waxy Cuticle, upper epidermis, palisade layer, spongy mesophyll, stomata, guard cells, and veins.

Question 22

How does a large surface area help a leaf photosynthesize?

Answer 22

It allows the leaf to absorb more sunlight for photosynthesis.

Question 23

Why is the leaf thin?

Answer 23

To allow gases to diffuse quickly to cells.

Question 24

What is the function of the transparent cuticle and upper epidermis?

Answer 24

To allow sunlight to penetrate to the photosynthetic cells below.

Question 25

Why are chloroplasts mostly found in the palisade layer?

Answer 25

Because this layer is at the top of the leaf and gets the most light.

Question 26

What role do stomata play in photosynthesis?

Answer 26

They allow carbon dioxide to enter and oxygen to exit the leaf.

Question 27

What do guard cells do?

Answer 27

They control the opening and closing of the stomata.

Question 28

How does increasing light intensity affect photosynthesis?

Answer 28

It increases the rate of photosynthesis until a maximum rate is reached.

Question 29

How does increasing carbon dioxide affect photosynthesis?

Answer 29

It increases the rate up to a certain level, then it levels off.

Question 30

What happens to photosynthesis if the temperature is too high?

Answer 30

The enzymes denature, and the rate of photosynthesis drops.

Question 31

What would happen without photosynthesis?

Answer 31

There would be no oxygen or food for most living organisms, leading to extinction.

Question 32

How does photosynthesis help regulate the atmosphere?

Answer 32

It removes carbon dioxide, helping to control the Earth's temperature.

Question 33

Do plants do both photosynthesis and respiration?

Answer 33

Yes, they photosynthesize during the day and respire all the time.

Question 34

How can you show that chlorophyll is needed for photosynthesis?

Answer 34

Use a variegated leaf (green and white), do the starch test, and only the green parts will turn blue-black.

Question 35

How can you prove light is needed for photosynthesis?

Answer 35

Cover part of a leaf with foil, leave it in sunlight, then test for starch—only exposed areas turn blue-black.

Question 36

What do you count in the Elodea (aquatic plant) experiment to measure the rate of photosynthesis?

Answer 36

The number of oxygen bubbles released per minute.

Question 37

What does the starch test prove in a leaf?

Answer 37

That photosynthesis has occurred, producing starch (glucose stored as starch).

Question 38

What are the steps to test a leaf for starch?

Answer 38

Boil in water → Boil in alcohol → Rinse in warm water → Add iodine.

Question 39

Why do you boil the leaf in water first?

Answer 39

To kill the cells and stop all chemical reactions

Question 40

Why do you boil the leaf in alcohol?

Answer 40

To remove chlorophyll so the iodine test result is clearly visible.

Question 41

Why do you rinse the leaf in warm water after the alcohol?

Answer 41

To soften the leaf, as alcohol makes it brittle.

Question 42

What does a blue-black color after adding iodine indicate?

Answer 42

That starch is present and photosynthesis occurred.

Question 43

What adaptations make the leaf efficient at photosynthesis?

Answer 43

Large surface area to absorb more sunlight Thin structure allows gases to diffuse quickly Stomata allow gas exchange Chloroplasts are concentrated in the palisade layer Transparent cuticle allows light in Vascular tissues (xylem and phloem) transport water and food

Question 44

What are guard cells and what do they do?

Answer 44

Guard cells are specialized cells that surround stomata and control their opening and closing, helping regulate gas exchange and water loss.

Question 45

What is the role of chlorophyll in photosynthesis?

Answer 45

Chlorophyll traps sunlight energy, which is essential for the light-dependent stage of photosynthesis.

Question 46

What is needed for photosynthesis to occur?

Answer 46

Light, chlorophyll, carbon dioxide, and water.

Question 47

How does carbon dioxide reach the leaf cells?

Answer 47

It diffuses through the stomata into air spaces, then into the cells.

Question 48

How does light reach the chloroplasts?

Answer 48

Light passes through the transparent cuticle and upper leaf layers to reach chloroplasts, especially in the palisade layer.

Question 49

What happens to the oxygen produced in photosynthesis?

Answer 49

Some is used in plant respiration, and the rest diffuses out through the stomata.

Question 50

What is a limiting factor?

Answer 50

A condition that, if in short supply, slows the rate of photosynthesis even if other conditions are ideal.

Question 51

What are the main limiting factors of photosynthesis?

Answer 51

Light intensity Carbon dioxide concentration Temperature Availability of water

Question 52

How does temperature affect photosynthesis?

Answer 52

It affects enzyme activity; too low or too high can slow or stop photosynthesis.

Question 53

Why is carbon dioxide often a limiting factor?

Answer 53

Because its concentration in the atmosphere is low; in greenhouses, extra CO₂ is often added to increase yield.

Question 54

How does light intensity affect photosynthesis?

Answer 54

Low light reduces the rate; photosynthesis increases with more light, up to a point.

Question 55

When can water be a limiting factor?

Answer 55

During drought or dry conditions, water shortage limits photosynthesis.

Question 56

What is etiolation?

Answer 56

Etiolation is the abnormal growth of plants in darkness, where stems become long and pale with small yellow leaves due to lack of chlorophyll.

Question 57

Why does etiolation occur?

Answer 57

The plant uses stored food to grow and stretch towards light, trying to reach sunlight and resume normal photosynthesis.