#5 Take-home Exam

Question 1

Cell metabolism

Answer 1

The sum of all chemical reactions that occur in a cell

Question 2

Activation energy (in regards to enzymes)

Answer 2

represents a strain on a cell’s resources and cell’s have evolved mechanisms to lower this energy bill

Question 3

Stoma

Answer 3

A pore in a leaf for gas exchange

Question 4

Mesophyll (in regards to leaf anatomy)

Answer 4

inner tissue of leaf containing many chloroplasts

Question 5

Stroma

Answer 5

Fluid that fills space inside the chloroplast, where the Calvin Cycle occurs

Question 6

Thylakoid

Answer 6

Flattened sac containing chlorophyll where light reactions occur

Question 7

Chlorophyll

Answer 7

Green light-absorbing pigment

Question 8

NADPH

Answer 8

used in anabolic reactions. It temporally stores the electrons and provides reducing “power” (electrons) to the Calvin Cycle.

Question 9

NADH

Answer 9

delivers the two electrons to an electron transport chain in cellular respiration

Question 10

FADH2

Answer 10

an electron carrier that helps NADH shuttle electrons for the electron transport chain in cellular respiration

Question 11

What is the role of enzymes?

Answer 11

they function to speed up chemical reactions in the cell

Question 12

What does it mean that an enzyme and its substrate

interact like a “lock and key.”

Answer 12

Enzymes use a ‘lock and key’ process that allows specific enzymes to catalyze very specific reactions. In this analogy, the lock is the enzyme and the key is the substrate. Only the correctly sized key (substrate) fits into the key hole (active site) of the lock (enzyme)

Question 13

what is the role of the enzyme’s substrate, and the

enzyme’s active site

Answer 13

The substrateis a molecule upon which anenzymeacts and the enzymes active site is the region of an enzyme where substrate molecules bind and undergo a chemical reaction

Question 14

Why is it important that an enzyme lowers the activation energy needed
to kick-start the reaction that enzyme catalyzes.

Answer 14

Because the lower the activation energy for a reaction the faster the rate.

Lowers cell’s energy bill

Question 15

Explain how changing the temperature and pH effects the functionality (efficiency) of an enzyme

Answer 15

Each enzyme has an optimal temperature. If it gets too warm the enzyme loses its shape and can no longer function properly. If the temperature gets to cold then molecules move more slowly and enzyme activity decreases Enzymes also have an optimal pH for maximum efficiency if conditions are too basic or acidic the enzyme will denature

Question 16

How does increasing the concentration of an enzyme’s substrate effect the ability (efficiency) of
an enzyme to convert its substrate into product?

Answer 16

Because the substrate concentration must be high enough to come into contact with the reactants

Question 17

Where specifically do the light reactions of photosynthesis take
place?

Answer 17

in the thylakoid

Question 18

what is the first step of light reactions

Answer 18

Chlorophyll molecule in photosystem II absorbs the energy from a photon exciting an electron. That energy is passed along until it reaches the reaction center where it provides energy to an electron of P680. That electron jumps to a higher energy level.

Question 19

what is the second step of light reactions

Answer 19

2. The electron from P680 is captured by the primary electron acceptor.

Question 20

what is the third step of light reactions

Answer 20

3. H2O is split and its electrons are supplied to the P680 as the P680 is giving up its electron to the primary electron acceptor. The resulting oxygen atoms from the split H2O form O2 and leave as waste.

Question 21

what is the forth step of light reactions

Answer 21

4. The excited electron held by the primary electron acceptor passes from photosystem II to photosystem I via an electron transport chain. The fall of the electron down the chain drives a H+ pump that forces hydrogen ions up a concentration gradient from outside the thylakoid to inside the thylakoid space. This establishes a concentration gradient of H+ ions which is a source of stored potential energy.

Question 22

what is the fifth step of light reactions

Answer 22

5. Meanwhile a chlorophyll molecule in photosystem I absorbs the energy in a photon and presents that energy to the P700 in the reaction center complex. The primary electron acceptor captures the electron from the P700 and the electron provided by photosystem II replaces the excited electron leaving the P700 that is captured by the primary electron acceptor.

Question 23

what is the sixth step of light reactions

Answer 23

6. The excited electron from the primary electron acceptor passes through a short electron+ transport chain to NADP , reducing it to NADPH.

Question 24

what is the seventh step of light reactions

Answer 24

7. Meanwhile the H+ ions flow down their concentration gradient through a special protein channel called ATP synthase which makes ATP.

Question 25

Where specifically does the Calvin cycle take place?

Answer 25

In the stroma

Question 26

What happens during the Calvin cycle

Answer 26

The Calvin Cycle takes the energy in NADPH and ATP and stores it in glucose and then produces sugar

Question 27

What are the end products of the Calvin cycle?

Answer 27

Molecules of G3P

Question 28

Where specifically does glycolysis take place?

Answer 28

in the cytoplasm of a cell

Question 29

What are the end products of glycolysis?

Answer 29

harvests four electrons and makes two ATP molecules

Question 30

Where specifically does the Krebs cycle take place?

Answer 30

in the matrix of a cell

Question 31

What are the end products of the Krebs cycle?

Answer 31

for each molecule of pyruvate, the Krebs cycle harvests ten electrons and makes one one ATP molecules

Question 32

Where specifically does oxidative phosphorylation take place?

Answer 32

in the inner membrane of the mitochondria

Question 33

Briefly describe

what happens during oxidative phosphorylation

Answer 33

high energy electrons are being brought up to the top of the electron transport chain. they are then brought down the electron transport chain and drive hydrogen ion pumps. oxygen grabs electrons and grabs a hydrogen ion
oxygen + hydrogen = H20
H20 then goes away as a waste product

Question 34

What are the end products of oxidative phosphorylation?

Answer 34

end products are H+ concentration gradient, lots of ATP, as well as H2O as a waist product

Question 35

Compare and contrast the light reactions of photosynthesis and oxidative phosphorylation of cellular respiration explaining how they are “backward” images of one another.

Answer 35

Light reactions of photosynthesis and oxidative phosphorylation of cellular respiration are both redox reactions.
Photosynthesis is making food
while
cellular respiration consumes food and makes ATP.
Their chemical reactions are “backwards/flipped” in a sense.