Photosynthesis Flashcards
What is Nutrition?
The process by which organisms can utilise food for their basic needs.
What are the two types of nutrition?
Autotrophic
Heterotrophic
What are autotrophs?
Organisms who make their own food. They use simple, inorganic substances and either light energy (photosynthesis) or chemical energy to synthesise food.
What are heterotrophs?
Organisms who consume food made by autotrophs. They obtain energy through intake and digestion of organic substances (animals/tissue).
What is photosynthesis?
The process by which plants manufacture carbohydrates from raw materials using energy from light.
How is photosynthesis important on Earth?
It is important in maintaining levels of oxygen and carbon dioxide in the atmosphere.
What are the things that plants need for photosynthesis?
Carbon Dioxide;
Water;
Light (a source of energy);
Chlorophyll.
WhaT are the things produced by plants by photosynthesis?
Glucose
Oxygen
What is the word equation for Photosynthesis?
Carbon Dioxide + Water —– (Light + Chlorophyll) ——->
Glucose + Oxygen
What’s the Chemical Equation for Photosynthesis?
6 CO2 + 6 H2O ->
C6 H12 O6 +
6 O2
What is chlorophyll?
The green coloured pigment present in the chloroplasts of plant cells that trap energy from sunlight and convert it to chemical energy.
Why is sunlight needed for Photosynthesis?
Because it provides energy needed for the process.
In what color lights does photosynthesis take place effectively?
In red and blue lights.
In what colour lights does photosynthesis take place poorly?
Green light.
What are called the food factories of the plant?
Leaves.
Why are leaves considered the food factories of the plant?
Because they are the sites of photosynthesis.
What are stomata?
Leaves possess small pores called stomata on their surface.
Stomata are the structures which help in the exchange of gases.
Why are stomata present at the bottom of the leaf?
The bottom of the leaf is more shaded and cooler; stomata are located there to reduce excessive water loss because of exposure to sunlight.
Draw a plant cell:
Cytoplasm
Nucleus
Cell membrane
Cellulose cell wall
Mitochondria
Vacuole
Chloroplast
The leaf is a…
plant organ
What are the adaptations of leafs?
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)
What is the leaf adaptation (thin) used for?
Provides a short distance for carbon dioxide to move by diffusion into the leaf.
What is the leaf adaptation (TOP OF LEAF HAS A LARGE SURFACE AREA) used for?
To absorb a large amount of sunlight
What is the leaf adaptation (PALISADE MESOPHYLL LAYER) used for?
Has oblong shape cells to pack many cells together.
Contains a large number of chloroplasts to absorb light.
What is the leaf adaptation (SPONGY MESOPHYLL LAYER) used for?
Has air spaces for diffusion of gases
What is the leaf adaptation (WAXY CUTICLE) used for?
To reduce water loss.
Protects from pathogens.
What is the leaf adaptation (STOMATA) used for?
Allows carbon dioxide and oxygen to diffuse in and out of the leaf.
What is the leaf adaptation (GUARD CELLS) used for?
To open and close the stomata depending on the conditions.
What is the leaf adaptation (NETWORK OF TUBES -XYLEM AND PHLOEM-) used for?
Xylem: To transport water
Phloem: To transport sucrose
Label a cross section of a leaf:
Waxy Cuticle
Upper Epidermis
Mesophyll: Palisade Mesophyll; Spongy Mesophyll
Lower Epidermis: Stomata; Guard cell with chloroplasts; Wax cuticle.
What is a monosaccharide?
A monosaccharide contains only 1 sugar molecule.
What is a disaccharide?
When there are 2 sugar molecules.
What is a polysaccharide?
Many sugar molecules joined together by a polymerizaition reaction.
What’s an example of a monosaccharide?
Glucose.
What’s an example of Disaccharide?
Sucrose: it’s made when glucose and fructose are joined together.
What’s an example of a polysaccharide?
Starch contains many glucose molecules joined together by a polymerization reaction.
Explain an experiment to see whether light is needed for photosynthesis:
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.
Why do we do those steps?
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).
What are the observations made in this experiment?
The covered area was yellowish brown in colour and the area that was exposed to sunlight was blue-black in colour.
What are the conclusions drawn in this experiment?
Since the area that was exposed to sunlight was positive for the presence of starch, it confirms that light is needed for photosynthesis.
