Unit 3 5A: Photosynthesis

Question 1

Autotrophs

Answer 1

An organism which synthesizes its own organic materials (food), by capturing light energy and taking in inorganic compounds from its physical environment, to meets its energy needs

Question 2

Heterotrophs

Answer 2

An organism which ingests organic materials by feeding on autotrophs or on other organisms and their products, in order to convert energy in to the form of energy stored in ATP

Question 3

Photosynthesis

Answer 3

A chemical reaction in which light energy is used to convert the inorganic compounds carbon dioxide and water into the organic compound glucose; occurs in the chloroplast

Question 4

ATP

Answer 4

The main immediate source of chemical energy within a cell, powering most cellular processes, when a phosphate group is removed, energy is released and ADP is formed

Question 5

Cellular respiration

Answer 5

A chemical reaction in which the organic compounds glucose is broken down, producing various products (depending on presence or absence of oxygen) and energy in the form of ATP

Question 6

What type of chemical reaction is photosynthesis

Answer 6

Photosynthesis is an anabolic chemical reaction

Question 7

Chlorophyll

Answer 7

the green pigments on the thlylakoid membrain of the chloroplasts; absorbs light energy for photosynthesis

Question 8

What is the word equation for photosynthesis?

Answer 8

carbon dioxide + water –(Light energy, chloroplast)->
Oxygen+water+glucose

Question 9

Chlorophyll

Answer 9

The green pigment on the thylakoid membranes of the chloroplasts of green plants; Absorbs light energy for photosynthesis

Question 10

Granum

Answer 10

(Plural grana) a stack of thylakoid membranes inside the chloroplast of plant and algae cells

Question 11

Thylakoid membrane

Answer 11

Disc-shaped interconnected membrane-bound compartments inside a chloroplast that make up the grana and are the location of the pigment chlorophyll, and therefore the site of the light-dependent stage of photosynthesis.

Question 12

Stroma

Answer 12

The gel-like fluid inside a chloroplast which surrounds the grana; site of the light-independent stage of photosynthesis.

Question 13

Light-dependent stage

Answer 13

The first stage of photosynthesis; occurs in the thylakoid membranes and involves the splitting of water using light energy

Question 14

Light independent stage

Answer 14

The second stage of photosynthesis; occurs in the stroma of the chloroplast and involves the use of carbon dioxide to create glucose; also called the Calvin Cyle or Carbon Fixation

Question 15

Photolysis

Answer 15

The splitting of water using the light energy from the sun

Question 16

ADP (Adenine diphosphate)

Answer 16

A compound composed of adenosine and 2 phosphate groups that can store energy when another inorganic phosphate group is added, forming ATP

Question 17

NADP+

Answer 17

a coenzyme that accepts and transfers hydrogen ions from one place to another during photosynthesis

Question 18

Coenzyme

Answer 18

An organic molecule that contains carbon and binds to enzymes to help them to function; examples are NADP NAD and FAD

Question 19

RuBP

Answer 19

Ribose biphosphate, a 5C (5 carbon) compound that combines with carbon dioxide at the start of the Calvin Cycle of photosynthesis to form PGA

Question 20

Rubisco

Answer 20

RuBP Carboxylase, an enzyme that catalyses the formation of PGA by fixing carbon dioxide to RuBP during the Calvin Cycle of photosynthesis

Both Carbon dioxide and oxygen can both act as substrates which bind to the active site of rubisco

Has quaternary structure

Question 21

PGA

Answer 21

3-phosphoglycerate, a 3C (3 Carbon) compound formed when the enzyme Rubisco catalyses the attachment of a carbon from carbon dioxide to RuBP during the Calvin Cycle of photosynthesis

Question 22

PGAL

Answer 22

glyceraldehyde-3-phosphate, a 3C sugar that leads to the formation of glucose and regenerates RuBP in the process to continue the Calvin Cycle

Question 23

Light energy is converted into what form of energy during photosynthesis?

Answer 23

Chemical energy

Question 24

Name the collective term for the plant pigments that help chlorophyll harness light energy

Answer 24

Carotenoids

Question 25

Which two colours of the visible light spectrum are primarily absorbed by chlorophyll a and b?

Answer 25

Red and blue

Question 26

What is the waste product of photosynthesis

Answer 26

Oxygen

Question 27

Where does the Calvin Cycle take place?

Answer 27

The stroma

Question 28

Name the stage of photosynthesis where carbon dioxide is used

Answer 28

Light independent stage

Question 29

Name the enzyme that catalyses the formation of PGA

Answer 29

Rubisco

Question 30

Steps in te light dependent stage

Answer 30

1. When light energy is captured, it splits water (photolysis), producing oxygen (O2),
   hydrogen ions (H+) and electrons.
2. The oxygen is released, by diffusion, out of the thylakoid membrane to the stroma, into the atmosphere as a waste product of photosynthesis
3. Electrons released when light energy stimulates chlorophyll are used by ATP
   synthase, an enzyme embedded in the thylakoid membrane, to catalyse the
   synthesis of ATP from ADP and Pi (inorganic phosphate).
4. Hydrogen ions (also called protons) and some of the electrons released in the
   previous step are taken up by an acceptor molecule called NADP+, which then forms NADPH.
5. The hydrogen ions (via NADPH) and ATP produced during the light-dependent stage
   of photosynthesis are then transported to the stroma for the light-independent
   stage of photosynthesis.