week 18

Question 1

what is the first law of thermodynamics

Answer 1

no energy can be lost within the universe. energy can be converted from one form to another.

Question 2

what is the second law of thermodynamics

Answer 2

every energy transfer increases the entropy (chaos) of the universe. takes the environment into account.

Question 3

what is cellular respiration by definition

Answer 3

the metabolic process by which an organism obtains nutrients by oxidising them and releasing waste products.

Question 4

what is the difference between exergonic and endergonic reactions?

Answer 4

exergonic= energy is released
endergonic= energy is required

Question 5

describe the difference between anabolism and catabolism

Answer 5

anabolism= use of energy to build complex molecules e.g. protein synthesis
catabolism= release of energy through molecule breakdown, e.g. breakdown of glucose

Question 6

how does ATP release energy

Answer 6

releases energy when the outermost inorganic phosphate is removed. energy is stored in the outermost phosphate because the negative charges repel each other.

Question 7

name two ways ATP is formed

Answer 7

1. substrate level phosphorylation (transfer of phosphate group)
2. oxidative phosphorylation (chemiosmosis)

Question 8

what is chemiosmosis

Answer 8

movement of ions down their electrochemical gradient across a semipermeable membrane.

Question 9

what is the role of the enzyme kinase

Answer 9

adds a phosphate

Question 10

what is metabolism

Answer 10

the totality of an organism’s chemical reactions

Question 11

what is photosynthesis

Answer 11

a process that converts atmospheric CO2 and H2O into carbohydrates

Question 12

what are phototrophs

Answer 12

photosynthetic organisms

Question 13

what is involved in the light reaction of photosynthesis

Answer 13

they are membrane-bound, releasing O2 from splitting 2H2O. the hydride ion from H2O reduces NADP+ to NADPH.

Question 14

what is involved in the dark reaction of photosynthesis

Answer 14

occurs in solution, CO2 is reduced to carbohydrate, this required energy from NADPH and ATP

Question 15

what is an antenna pigment

Answer 15

they extend the range of light capture especially in green wavelength. Carotenoids

Question 16

what is photophosphorylation

Answer 16

synthesis on ATP, which is dependent on light energy

Question 17

how are dark reactions identified

Answer 17

fast CO2 injection, rapid ‘quench’ (perchloric acid) to stop reactions, 2D chromatography improves separation of intermediates

Question 18

what is the composition of RuBisCos subunists

Answer 18

8 small subunits and 8 large subunits. large subunits are nuclear-encoded and small subunits are chloroplast encoded

Question 19

what does photorespiration do

Answer 19

recycles toxic products of the oxygenation reaction. Consuming NADH, ATP and giving glyoxylate, serine, glycine and CO2

Question 20

what do the dark reactions do

Answer 20

uses NADPH and ATP with RuBisCo to fix CO2 and regenerate RuBP

Question 21

what types of photosynthesis are well suited to growth under high light and reduced water availability

Answer 21

C4 and CAM

Question 22

what are purines and pyrimidines

Answer 22

Purines have two fused rings (A and G) while pyrimidines have got one ring (C and T)

Question 23

what does a nucleotide consist of

Answer 23

a base, the sugar deoxyribose and a phosphate.

Question 24

what does DNA ligase do

Answer 24

joins fragments of new DNA from the lagging strand

Question 25

In what direction does DNA replication occur

Answer 25

5' -> 3'

Question 26

define the difference between catabolic and anabolic reactions

Answer 26

catabolic= breakdown of molecules into smaller ones, energy released anabolic= build-up of molecules requiring energy

Question 27

what are antenna pigments

Answer 27

they extend the range of light capture, especially in the green wavelength

Question 28

how is light absorbtion organised

Answer 28

between two photosystems (PSI and PSII)

Question 29

what is the cytochrome b6f complex and its role in photosynthesis

Answer 29

a protein in the thylakoid membrane involved in transporting electrons between photosystem I and II

Question 30

what light (nm) are the photosystems PSI and PSII paired to capture

Answer 30

PSI= P700 (absorbs light maximally at 700nm) PSII= P800 (absorbs light maximally at 680nm)

Question 31

what is the z scheme

Answer 31

the path of electron flow and reduction potentials. absorbing light energy converts P680 and P700 into excited molecules (better reducing agents). light energy drives electron flow uphill, NADP+ is reduced to NADPH. antenna pigments capture light.

Question 32

what is the chloroplast structure

Answer 32

4-8mm diameter with two membranes, internal membrane (thykaloid membrane) stacking

Question 33

what is the cyclic electron flow

Answer 33

an alternative electron transport pathway which produces ATP without generating NADPH

Question 34

what is photophosphorylisation

Answer 34

process where light energy is used to generate ATP in photosynthetic organisms

Question 35

what is chloorplast ATP synthase

Answer 35

an enzyme which synthesises ATP in chloroplasts consisting of two major particles, CF0 and CF1.

Question 36

what is chemiosmosis

Answer 36

a process where the movement of ions across a membrane down their electrochemical gradient is used to generate ATP

Question 37

what are pyrenoids

Answer 37

membrane-bound structures found in the chloroplast of some algae. some (like carboxysomes) include rubisco and concentrate co2

Question 38

what is C4 photosynthesis

Answer 38

an alternative photosynthetic strategy to get around limited rubisco. four carbons, hatch-slack pathway

Question 39

what is CAM photosynthesis

Answer 39

saves water use, using an inverted stomatal opening/ closing to save water and concentrate co2 in the leaf. stomata are closed during the day and open at night.

Question 40

whats the difference between C3 and C4 photosynthesis

Answer 40

C3- most common pathway, produces a 3 carbon molecule. more common in cooler more humid environments. C4- produces a four carbon molecule. more effiecient in hot/ dry enviroments

Question 41

what end of the DNA strand are nucleotides added

Answer 41

3'

Question 42

Each time a molecule of glucose is completely oxidized via aerobic respiration, how many oxygen (O2) molecules are required

Answer 42

6

Question 43

Which process in eukaryotic cells will normally proceed whether O2 is present or absent

Answer 43

glycolysis

Question 44

a gene is usually..

Answer 44

the info for making a polypeptide

Question 45

what is substrate level phosphorylisation

Answer 45

form of making ATP when a phosphate is transferred to ADP to make ATP. it doesnt need oxygen

Question 46

The first event of translation in eukaryotes (starting with methionine) is the...

Answer 46

base pairing of met-tRNA to AUG of the messenger RNA.

Question 47

define allometric growth

Answer 47

when different parts of the organism grow at different rates

Question 48

what is hybrid inviability

Answer 48

a postzygotic reproductive barrier where a fertilised egg from two different species fails to develop properly