Photosynthesis

Question 1

What is Nutrition?

Answer 1

The process by which organisms can utilise food for their basic needs.

Question 2

What are the two types of nutrition?

Answer 2

Autotrophic

Heterotrophic

Question 3

What are autotrophs?

Answer 3

Organisms who make their own food. They use simple, inorganic substances and either light energy (photosynthesis) or chemical energy to synthesise food.

Question 4

What are heterotrophs?

Answer 4

Organisms who consume food made by autotrophs. They obtain energy through intake and digestion of organic substances (animals/tissue).

Question 5

What is photosynthesis?

Answer 5

The process by which plants manufacture carbohydrates from raw materials using energy from light.

Question 6

How is photosynthesis important on Earth?

Answer 6

It is important in maintaining levels of oxygen and carbon dioxide in the atmosphere.

Question 7

What are the things that plants need for photosynthesis?

Answer 7

Carbon Dioxide;
Water;
Light (a source of energy);
Chlorophyll.

Question 8

WhaT are the things produced by plants by photosynthesis?

Answer 8

Glucose
Oxygen

Question 9

What is the word equation for Photosynthesis?

Answer 9

Carbon Dioxide + Water —– (Light + Chlorophyll) ——->
Glucose + Oxygen

Question 10

What’s the Chemical Equation for Photosynthesis?

Answer 10

6 CO2 + 6 H2O ->
C6 H12 O6 +
6 O2

Question 11

What is chlorophyll?

Answer 11

The green coloured pigment present in the chloroplasts of plant cells that trap energy from sunlight and convert it to chemical energy.

Question 12

Why is sunlight needed for Photosynthesis?

Answer 12

Because it provides energy needed for the process.

Question 13

In what color lights does photosynthesis take place effectively?

Answer 13

In red and blue lights.

Question 14

In what colour lights does photosynthesis take place poorly?

Answer 14

Green light.

Question 15

What are called the food factories of the plant?

Answer 15

Leaves.

Question 16

Why are leaves considered the food factories of the plant?

Answer 16

Because they are the sites of photosynthesis.

Question 17

What are stomata?

Answer 17

Leaves possess small pores called stomata on their surface.
Stomata are the structures which help in the exchange of gases.

Question 18

Why are stomata present at the bottom of the leaf?

Answer 18

The bottom of the leaf is more shaded and cooler; stomata are located there to reduce excessive water loss because of exposure to sunlight.

Question 19

Draw a plant cell:

Answer 19

Cytoplasm
Nucleus
Cell membrane
Cellulose cell wall
Mitochondria
Vacuole
Chloroplast

Question 20

The leaf is a…

Answer 20

plant organ

Question 21

What are the adaptations of leafs?

Answer 21

Thin

Top of leaf has a large surface area

Palisade Mesophyll layer

Spongy Mesophyll layer

Waxy cuticle

Stomata

Guard cells

Network of tubes (xylem and phloem)

Question 22

What is the leaf adaptation (thin) used for?

Answer 22

Provides a short distance for carbon dioxide to move by diffusion into the leaf.

Question 23

What is the leaf adaptation (TOP OF LEAF HAS A LARGE SURFACE AREA) used for?

Answer 23

To absorb a large amount of sunlight

Question 24

What is the leaf adaptation (PALISADE MESOPHYLL LAYER) used for?

Answer 24

Has oblong shape cells to pack many cells together.

Contains a large number of chloroplasts to absorb light.

Question 25

What is the leaf adaptation (SPONGY MESOPHYLL LAYER) used for?

Answer 25

Has air spaces for diffusion of gases

Question 26

What is the leaf adaptation (WAXY CUTICLE) used for?

Answer 26

To reduce water loss. Protects from pathogens.

Question 27

What is the leaf adaptation (STOMATA) used for?

Answer 27

Allows carbon dioxide and oxygen to diffuse in and out of the leaf.

Question 28

What is the leaf adaptation (GUARD CELLS) used for?

Answer 28

To open and close the stomata depending on the conditions.

Question 29

What is the leaf adaptation (NETWORK OF TUBES -XYLEM AND PHLOEM-) used for?

Answer 29

Xylem: To transport water Phloem: To transport sucrose

Question 30

Label a cross section of a leaf:

Answer 30

Waxy Cuticle Upper Epidermis Mesophyll: Palisade Mesophyll; Spongy Mesophyll Lower Epidermis: Stomata; Guard cell with chloroplasts; Wax cuticle.

Question 31

What is a monosaccharide?

Answer 31

A monosaccharide contains only 1 sugar molecule.

Question 32

What is a disaccharide?

Answer 32

When there are 2 sugar molecules.

Question 33

What is a polysaccharide?

Answer 33

Many sugar molecules joined together by a polymerizaition reaction.

Question 34

What's an example of a monosaccharide?

Answer 34

Glucose.

Question 35

What's an example of Disaccharide?

Answer 35

Sucrose: it's made when glucose and fructose are joined together.

Question 36

What's an example of a polysaccharide?

Answer 36

Starch contains many glucose molecules joined together by a polymerization reaction.

Question 37

Explain an experiment to see whether light is needed for photosynthesis:

Answer 37

1) Choose a plant, and keep it in the dark for 24 hours. 2) Select a leaf and cover a part of the leaf with black paper/aluminum foil. Leave the plant expose to sunlight for at least 6 hours. 3)Take the leaf and boil for 2 minutes in the water. 4) Heat the leaf in ethanol bath. 5) Wash the leaf with a little distilled water. 6)Place it on a white tile and add a few drops of iodine solution.

Question 38

Why do we do those steps?

Answer 38

1) This is to destarch or remove previously-made starch from the leaves. This step is important to prove that any starch present at the end of this experiment has been produced due to photosynthesis. 2)The leaves of the plant exposed to sunlight will carry out photosynthesis and produce starch. The area covered in black paper, will not be able to carry out photosynthesis. No starch will be produced. 3)This is to stop durther chemical reactions in the plant cells and also to breakdown the cell walls. 4) Remove the chlorophyll inside the leaf. It will decolorise the leaf. If the green colour is present, we will not be able to see the colour change in the final step when we add the chlorophyll. 5) After boiling in ethanol, the leaf becomes fragile. To make it soft again, we wash it in distilled water. 6)To test if starch is present. Starch reacts with iodine (brown colour) and becomes blue-black in colour. If starch is absent, the leaf will show a brown colour (since iodine is brown).

Question 39

What are the observations made in this experiment?

Answer 39

The covered area was yellowish brown in colour and the area that was exposed to sunlight was blue-black in colour.

Question 40

What are the conclusions drawn in this experiment?

Answer 40

Since the area that was exposed to sunlight was positive for the presence of starch, it confirms that light is needed for photosynthesis.