Download Photosynthesis Questions

ALE #3 Energy
Name___________________________________
Energy general
1) Discuss how photosynthesis and respiration are related to each other, using the
first law of thermodynamics in your answer.
The first law of thermodynamics states that energy cannot be created or
destroyed, only changed to different forms. In photosynthesis, plants absorb
energy from the sun, and store it in the chemical bonds of glucose. This energy
stored in glucose is then harvested by all organisms on earth (plants and animals
both) as fuel for cellular respiration. In cellular respiration, cells break down
glucose and store the energy from its bonds in the molecule ATP. ATP can then
be used to power all of the cell’s work. The products of photosynthesis, oxygen
and glucose, are the reactants of cellular respiration. The products of cellular
respiration, carbon dioxide and water, are the reactants of photosynthesis.
2) What is ATP and how is it generated?
ATP is adenosine triphosphate. It is a high-energy carrier molecule, which is used to
power all cellular work. ATP gives up phosphate group to molecules, which gives them
energy to react (called phosphorylation). It is generated by electron transfer chains.
Photosynthesis
3) What is the purpose of the Calvin cycle? What molecules are produced?
The purpose of the Calvin cycle is to convert carbon dioxide into glucose molecules. The
molecule produced in its reactions are glucose, ADP, and NADP+
4) Where do the Calvin cycle reactions occur? (specific) Oxygen gas is released as a
byproduct of the splitting of water in the photosystem.
5) Where do the oxygen atoms (in oxygen gas) come from in photosynthesis?
The splitting of water by photosystem II
6) Where do the light reactions of photosynthesis occur? (specific)
The thylakoid membrane of the chloroplast
7) Which pigment is directly involved in the light reactions of photosynthesis? What role
does it play in the light reactions?
1
Chlorophyll is the main photosynthesis pigment. Chlorophyll molecules work together to
absorb photons of light. As the molecules absorb sunlight, they kick their electrons up to
a high energy state. These electrons are then passed down the electron transfer chain,
generating ATP.
8) In the following space, describe the steps of the light reactions. With the description
of each step, draw a diagram that helps to understand what happens in that step.
Description of step
Photosystem absorbs light, splitting water
into H+, electrons, and O2.
Drawing
These will vary. Use the diagrams in your
textbook as a guide
Further light absorption by the photosystem
kicks the electrons up to an excited state.
Excited electrons are passed along an
electron transport chain (proteins in the
thylakoid membrane)
Energy released at every step of electron
transport used to drive ATP synthesis
2
Further light absorption by a second
photosystem kicks the electrons up to
another excited state, passing the electrons
off to generate NADPH.
9) Why is chlorophyll green? It reflects green light and absorbs all other wavelengths of
visible light.
10) What is a photosystem and what do they do?
Photosystems are units of chlorophyll & accessory pigments. They work together to
absorb a photon of light. The absorbtion of light kicks electrons up to an excited, high
energy state.
Cellular Respiration
11) What is cellular respiration? Define.
The breakdown of glucose to create ATP, which is used to power all cellular work.
12) Fill in the following summary table for Aerobic cellular respiration:
Step:
Reactants (going into)
Products (coming out)
Glycolysis
Glucose, ATP
2 pyruvic acid, ATP,
NADH
Kreb’s cycle
Acetyl Co-A (derived
from pyruvic acid),
NAD+, FAD, ADP
NADH, FADH2, ADP,
O2
CO2, ATP, NADH,
FADH2
2
ATP, H20, NAD+, FAD
32-34
Electron transfer
chain
13) Why is oxygen needed for Aerobic cellular respiration?
Oxygen is the final electron acceptor of the electron transfer chain.
3
# ATP
produced (net)
2
14) From your reading (plants and people page 86): How does skunk cabbage grow up
through the snow and attract insect pollinators?
Skunk cabbage produces a large amount of heat that melts through the snow, allowing the
plant to grow up out of the snow. The heat is generated by cellular respiration. The
plants produce a large amount of heat, due to a large concentration of mitochondria. The
heat also helps to produce volatile organic compounds (odors). Both the heat and odor
help to attract insects. Have you ever smelled skunk cabbage? It stinks!
4