Unit 3-> Photosynthesis

Question 1

What is the independent variable in an experiment?

Answer 1

The variable that is manipulated or changed by the experimenter

It is often considered the cause in a cause-and-effect relationship.

Question 2

What is the dependent variable in an experiment?

Answer 2

The variable that is measured or observed in response to changes in the independent variable

It is often considered the effect in a cause-and-effect relationship.

Question 3

What are controlled variables?

Answer 3

Variables that are kept constant throughout an experiment

They ensure that the experiment tests only the impact of the independent variable.

Question 4

What distinguishes an experimental group from a control group?

Answer 4

The experimental group receives the treatment, while the control group does not

This allows for comparison to assess the effect of the treatment.

Question 5

Define autotrophs.

Answer 5

Organisms that produce their own food through photosynthesis or chemosynthesis

examples: plants

Examples include plants and some bacteria.

Question 6

Define heterotrophs.

Answer 6

Organisms that cannot produce their own food and must consume other organisms

examples: animals

Examples include animals and fungi.

Question 7

Which type of organism performs photosynthesis?

Answer 7

Autotrophs

They convert light energy into chemical energy.

Question 8

Which type of organism would eat the other?

Answer 8

Heterotrophs eat autotrophs

This is part of the food chain.

Question 9

What is ATP?

Answer 9

Adenosine triphosphate, the energy currency of the cell

It stores and transfers energy within cells.

Question 10

What is ADP?

Answer 10

Adenosine diphosphate, a lower-energy molecule than ATP

It is formed when ATP loses a phosphate group.

Question 11

What are the components of ATP?

Answer 11

Adenine, ribose, and three phosphate groups

The energy is stored in the bonds between the phosphate groups.

Question 12

How does ATP convert to ADP?

Answer 12

By losing one phosphate group and releasing energy

This process is reversible, allowing cycling between ATP and ADP.

Question 13

Where is energy stored in ATP?

Answer 13

In the bonds between the phosphate groups

Breaking these bonds releases energy for cellular processes.

Question 14

What is the difference between wavelength and frequency?

Answer 14

Wavelength is the distance between successive peaks of a wave, while frequency is the number of peaks that pass a point in one second

They are inversely related; as one increases, the other decreases.

Question 15

What are the three types of light interaction with materials?

Answer 15

Absorption, reflection, transmission

These interactions determine how light behaves when it encounters different surfaces.

Question 16

What pigment is primarily involved in photosynthesis?

Answer 16

Chlorophyll

It absorbs light energy, primarily in the blue and red wavelengths.

Question 17

Where is chlorophyll located in plant cells?

Answer 17

In the chloroplasts

Chloroplasts are the sites of photosynthesis.

Question 18

What is the balanced equation of photosynthesis?

Answer 18

6CO2 + 6H2O + light energy → C6H12O6 + 6O2

This shows the conversion of carbon dioxide and water into glucose and oxygen.

Question 19

What factors affect the rate of photosynthesis?

Answer 19

• Light intensity
  ->needed for light dependent reactions
• Carbon dioxide concentration
  ->a key reactant in the light-independent (Calvin cycle) reaction
• Temperature
  ->impacts the activity of enzymes involved in the process
• Water availability
  ->a reactant in the light-dependent reactions, and also because water scarcity can lead to stomata closure, limiting carbon dioxide uptake

Each factor influences the efficiency of photosynthesis.

Question 20

What are the reactants of the Light Dependent Reactions?

Answer 20

Water and light energy

possibly ADP and NADP+

These are converted into oxygen and energy carriers (ATP and NADPH).

Question 21

What are the products of the Light Dependent Reactions?

Answer 21

Oxygen, ATP, and NADPH

Oxygen is released as a byproduct.

Question 22

Where do the Light Dependent Reactions occur?

Answer 22

In the thylakoid membranes of the chloroplasts

This location is essential for light absorption.

Question 23

What are the main intermediates of the Calvin Cycle?

Answer 23

• RUBP
  ->catalyzes the reaction
• PGA
  ->formed during carbon dioxide fixation and is a precursor to the synthesis of sugars
• G3P (PGAL)
  ->G3P is a product of the reduction of 3-phosphoglycerate (PGA) and is used to regenerate the starting molecule (RuBP) for the cycle to continue

These molecules play critical roles in carbon fixation and sugar production.

Question 24

Which products of the Light Dependent Reactions interact with the Calvin Cycle?

Answer 24

ATP and NADPH

These provide the energy and reducing power needed for carbon fixation.

Question 25

What are the reactants of the Calvin Cycle?

Answer 25

Carbon dioxide and ATP/NADPH ## Footnote These are converted into glucose.

Question 26

What are the products of the Calvin Cycle?

Answer 26

Glucose and other carbohydrates ADP and NADP+ ## Footnote These serve as energy sources for the plant.

Question 27

What distinguishes C4 plants from CAM plants?

Answer 27

C4 plants use a different pathway to fix carbon dioxide, while CAM plants fix carbon at night ## Footnote This adaptation helps them conserve water in arid conditions.

Question 28

What is absorption in light?

Answer 28

matter captures electromagnetic radiation (light) and converts its energy into other forms, like heat or chemical energy

Question 29

What is reflection in light?

Answer 29

the phenomenon where light bounces off a surface, changing direction but remaining in the same medium

Question 30

What is transmission in light?

Answer 30

the passage of electromagnetic radiation (like light) through a medium without significant absorption or reflection

Question 31

What are the 5 steps of the Light Dependent Cycle?

Answer 31

1. Pigments in Photosystem II absorb light, which breaks water molecules and excites electrons 2. Excited electrons leave Photosystem II and travel down the electron transport chain towards Photosystem I. At the same time, H+ ions are pumped via active transport across the thylakoid membrane into the thylakoid, creating a positive charge inside. 3. Electrons are re-energized in Photosystem I. 4. Electrons leave Photosystem I and travel down the electron transport chain. The electrons are eventually picked up by the electron carrier NADP+, which becomes NADPH. 5. H+ ions diffuse out of the thylakoid, passing through ATP synthase, which creates ATP.

Question 32

What are the 4 steps of the Calvin Cycle (light-independent cycle)?

Answer 32

1. Carbon fixation - each carbon dioxide molecule is added to a five-carbon molecule by an enzyme 2.The 6-carbon compound splits into two 3-carbon compounds. Phosphate groups from ATP and electrons from NADPH are added to make 3-carbon sugars. 3.One of the 3-carbon sugars is used to make organic compounds, like carbs and high-energy sugars (like glucose), which are stored for later. 4.The other 3-carbon sugars are used to regenerate the 5-carbon molecule from the beginning.