Photosynthesis

Question 1

Photosynthesis

Answer 1

Photosynthesis converts, light energy to the chemical energy or food. Organisms obtain organic compounds by one of two major modes autotrophic nutrition or heterotrophic nutrition

Question 2

The structural organization of chloroplasts

Answer 2

Allows for the chemical reaction of photosynthesis. Mainly found in mesophyll, the interior tissue of the leaf. CO2 enters in 02 exits, the leaf through microscope it pours cold stromata. A chloroplast has an envelope with two membrane surrounding a dense fluid called a stroma 

Question 3

Thylakoids

Answer 3

Thylakoids are connected sacks in the chloroplast that compose a third membrane system. They may be stacked in columns, called grana. Chlorophyl Resides in the thylakoid Membranes.

Question 4

The overall chemical change during photosynthesis is the reverse of the one that occurs during cellular respiration

Answer 4

Chloroplast split H2O into hydrogen and oxygen incorporating the electrons of hydrogen into sugar molecules, and releasing oxygen as a byproduct

Question 5

Redox process

Answer 5

Photosynthesis is redox process in which H2O’s oxidized and CO2 is reduced photosynthesis is an endergonic process; The energy boost is provided by light.

Question 6

Photosynthesis occurs and two Phases

Answer 6

The light reactions and the Calvin cycle

Question 7

The light reactions

Answer 7

Occurs at the thylakoid (granum) membrane (photo part) contains the chlorophyl

Question 8

The Calvin cycle

Answer 8

Occurs in the stroma (synthesis part)

Question 9

Part of the light reactions cycle

Answer 9

The light reactions convert solar energy to chemical energy. The light energy absorbed by chlorophyl in the thylakoid drives the transfer of electrons in hydrogen from water to NADP+, forming NADPH Carries these electrons to the Calvin cycle.

Question 10

Photosystem

Answer 10

a system is composed of a reaction centre surrounded by light harvesting complex of a few hundred pigment molecules

Question 11

Reaction centre

Answer 11

At the reaction centre is a primary electron acceptor which accepts an excited electron from the reaction centre chlorophyl

Question 12

Two types of photosystems in the thylakoid membrane

Answer 12

Photosystem l in photosystem ll. These two photos systems work together to use light energy to generate ATP and NADPH.

Question 13

During the light reactions, there are two possible routes for Electron flow 

Answer 13

The linear electron flow and the cyclic electron flow

Question 14

Linear electron flow (7steps)

Answer 14

1- Photosystem two absorbs, a photon of light and an electron is excited to a higher energy state.
2- This electron is captured by the primary electronic acceptor.
3- Electrons from water are used to replace those lost by the reaction center. This reaction creates O2 as a byproduct.
4- Excited electrons pass along an electron transport chain before ending up at the reaction centre of photosystem one. Their energy is used to produce ATP, which is used by the Calvin cycle.
5- Light energy has accident and electron of the reaction centre of photosystem one. The electron was captured by photosystem, one primary electron, acceptor, But is replaced by an electron that reaches the bottom of the electron transport chain from photosystem two.
6- Photo excited electrons are passed from photosystem, one primary Acceptor down a second electron transport chain.
7- Electrons from this chain are transferred to NADP+ , Forming NADPH, which will carry these high energy electrons to the Calvin cycle.

Question 15

What does the linear electron flow produce?

Answer 15

The linear electron flow produces ATP from NADPH in roughly equal quantities, but the Calvin cycle consumes more ATP than NADPH.

Question 16

Cyclic Electron flow( PS1 only)
(3 steps)

Answer 16

1- Excited electrons cycle from the reaction centre to a primary sector, along the Electron chain transport, and return to the oxidize reaction centre.
2- As electrons flow along the electron transport chain, they generate ATP, but there is no production of NADPH and no release of oxygen.
3- Cyclic electron flow allows the chloroplast to generate enough surplus ATP to satisfy the higher demand for ATP in the Calvin cycle.

Question 17

chemosmosis

Answer 17

Chloroplast and mitochondria generate ATP by the same mechanism chemosmosis (the movement of ions)

Question 18

The Calvin cycle (the synthesis part)

Answer 18

The Calvin cycle Uses ATP and NADPH from the light reactions to convert CO2 from the atmosphere into a three carbon sugar. The purpose is to reduce low energy CO2 into high energy sugar. The energy needed comes from ATP while the electrons needed come from NADPH, which are both produced by light reactions.

Question 19

The Calvin Cycle (3 steps)

Answer 19

1- Carbon fixation: Each CO2 molecule is attached to a five carbon sugar, RuBP To form a six carbon sugar. This is catalyzed by the enzyme Rubisco. The six carbon intermedia it’s unstable and splits to form a two 3 carbon molecule
2- Reduction: Each three carbon intermediate is reduced by a pair of electrons from NADPH producing G3P, Some of which connects with the cycle and be used by the plant sale to make glucose, Starch, cellulose and other molecules
3- Regeneration: The remaining G3P Are used to regenerate RuBP. In a complex series of reactions, the carbon skeletons of five molecules of G3P Are rearranged to regenerate three molecules of RuBP.

Question 20

What percent of the products from photosynthesis is consumed as fuel for cellular respiration?

Answer 20

About 50% of the product from photosynthesis is consumed us feel for cellular respiration, implant mitochondria. Most of the rest is used to make cellulose/starch.