Week 5

Question 1

What is Photosynthesis?

Answer 1

An anabolic process by which the energy of sunlight is harvested and used to convert CO2 into more comples molecules

Question 2

Photosynthesis is endoergonic or esoergonic?

Answer 2

Endoergonic (It requires energy from the sun)

Question 3

A compound that lose an electron become:

Answer 3

Oxydized

Question 4

A compound that gain an electron become:

Answer 4

Reduced

Question 5

Where does Photosynthesis take place?

Answer 5

Inside Thylakoids which are located inside the chloroplasts

Question 6

What happen during Light reactions?

Answer 6

Light reactions convert energy from the sun into chemical energy in the form of ATP and the reduced electron carrier NADPH

Question 7

What happen during light-independent reactions?

Answer 7

Don’t use light directly, instead they use ATP, NADPH and CO2 to produce carbohydrates

Question 8

What are pigments?

Answer 8

Molecules that absorb wavelenghts in the visible spectrum

Question 9

What does chlorophyll drives?

Answer 9

Chlorophyll drives the production of ATP and NADPH

Question 10

What are ATP and NADPH used for in the Calvin Cycle?

Answer 10

They’re used to fix CO2 and produce sugar

Question 11

When a photon meets a molecule it can interact in 3 ways:

Answer 11

• Scattered
• Transmitted
• Absorbed

Question 12

What happen when a photon is absorbed?

Answer 12

Absorption transfers the energy from the photon to the molecule and the molecule become excited

Question 13

Why are the plants green?

Answer 13

When a photon of a particular wavelenght it a plant it will be absorbed but green photons are reflected

Question 14

List the different types of Photosynthetic pigments:

Answer 14

• Chlorophyll a
• Chlorophyll b
• Accessory pigments

Question 15

What’s the role of accessory pigments?

Answer 15

Absorb different light spectrum and transfer their energy to chlorophyll

Question 16

What can happen when a pigment absorb a photon?

Answer 16

The energy can be:

• Released as heat/light
• Transferred to another molecule
• Used to drive a chemical reaction

Question 17

What’s the structure of chlorophyll?

Answer 17

It has got a magnesium ion that coordinates the flat structure and a long carbon tail which attach it to a protein structure

Question 18

What do photosystems do?

Answer 18

They harvest photon to excite chlorophyll which will pass the nergy to another chlorophyll molecule until it reaches the reaction center.

Question 19

What happen when the energy is passed to a reaction center in the photosystem?

Answer 19

The last excited chlorophyll will pass its electron to an electron acceptor

Question 20

Describe the features of Photosystem II

Answer 20

It’s primary donor is P680, a photon reaches the chlorophyll, it will absorb its energy an pass it to P680 (The reaction center).

Question 21

How does the reaction center get an electron back?

Answer 21

By oxydizing water

Question 22

Describe the features of Photosystem I

Answer 22

It’s primary donor is P700, which mean that it’s activated by less energy. It will cause the electron to move up and consequently 2 electron will reach NADP+ reductase

Question 23

What’s NADP+ reductase

Answer 23

It’s an enzyme that will cause the reduction of NADP+ to NADPH

Question 24

What’s the name of the process that link the 2 photosystem?

Answer 24

The Z scheme

Question 25

Describe the cyclic electron transport

Answer 25

In this electron transport the electron goes back into the same photosystem causing production of ATP.

Question 26

What's chemiosmotic production of ATP?

Answer 26

It's a process that occurs as the electron is passed down the transport chain it causes protons (H+) to be bumped in the lumen (against osmotic gradient so it requires energy). At the end all these electron pass through a special molecul called ATP synthase which produce ATP as protons pass through it.

Question 27

Why is the production of ATP called chemi-osmotic?

Answer 27

Because it involves two gradients: One of ion/charges and one of concentration.

Question 28

What are the 3 phases of Calvin Cycle?

Answer 28

Carbon fixation Reduction and sugar production Regeneration of the CO2 acceptor

Question 29

What's the role of riboluse bisphospate?

Answer 29

It's a five carbon acceptor

Question 30

When did photosynthesis first appeared?

Answer 30

2.7 billion years ago

Question 31

What was used for photosynthesis instead of water?

Answer 31

Hydrogne Sulfide (H2S)

Question 32

How may photosynthesis have evolved?

Answer 32

The depending on sulfide limited the process so photosynthetic organisms started using H2O which required a stronger oxidizing agent. Therefore it required the evolution of photsystem II.

Question 33

What are the advantages of multicellularity?

Answer 33

- Avoidance of predation - Overgrowth of unicellular competitors - Expanded feeding opportunities - Creation of protected internal environments - Novel metabolic opportunities - Enhanced motility and dispersal

Question 34

What's avoidance of predation:

Answer 34

Unicellular organisms have only engulfment as a way of predation, but as the prey become bigger it become difficult to eat it. However become bigger it's a problem so by combining with other cell you overcome the problem and you can enlarge.

Question 35

What's overgrowth of unicellular competitors?

Answer 35

When you're an individual you'll grow at your own rate but when you're multicellular you can make some cell specialize in growing faster so you outcompte unicellular organisms.

Question 36

What are the 3 criteria of multicellular organisms and not the colonies?

Answer 36

- Their cells must be held together by a multicellular matrix - Their cells must be able to comunicate with eacht other and respond to signals in a coordinated way - They must have to include different type of cells, each specialise in a particular role.

Question 37

What are the basic requirements for a multicellular organism?

Answer 37

- Cell adhesion - Cell signaling and coordination - Programmed cell death (apoptosis) - Capacity for cellular differentiation

Question 38

In which two ways could the first multicellular organism have arisen?

Answer 38

1) Clonal development by division of a single cell | 2) Aggregation of individual cells