Bio Paper 1

Characteristics of eukaryotes that prokaryotes don’t have

nucleus

membrane bound organelles

80S ribosomes

DNA associated in chromosomes

Why is it bad to use too diluted samples when doing direct counts

extra dilution gives additional error

inaccurate representation of whole sample

not valid to count less than 30 colonies

too few to be statistically significant

Is E. coli Gram Positive or Negative, and what shape

Gram Negative

Would appear red after gram staining

Bacillus/rod shaped

obligate aerobes

bacteria that grow in the presence of oxygen

Obligate anaerobes

bacteria that will only grow in the absence of oxygen

Facultative anaerobes

Bacteria that can grow with or without oxygen, but grow best with oxygen

ways that agar types could differ in composition

different pH

different C concentration

different N concentration

different growth factors

different concentration of vitamins/minerals

why would gram negative be more likely to cause illness than gram positive

the outer lipopolysaccharide layer protects against some antibiotics and makes them less susceptible to attack by lysozyme

Features of globular proteins

Features of globular proteins include:

• spherical

• They have a tertiary structure

• (They are) water soluble

What are lysozymes

An enzyme found in many secretions of the body like tears, saliva. It is able to break down the peptidoglycan cell walls of bacteria and form part of bodys chemical defence system against pathogens

how would you use serial dilutions to carry out a viable count

prepare number of sterile nutrient agar plates

transfer 1cm3 on to each separate plate from each of your serial dilutions

spread with sterile spreader

incubate at suitable temp like 25c

count colonies, 1=1cell

strategies to prevent overfishing

quotas so less fish are caught

minimum net mesh size so don’t catch younger or smaller fish

seasonal restrictions so don’t catch breeding fish so stocks can recover

consequences of deforestation

Soil erosion - soil is no longer protected from rain by the canopy, as roots decompose they no longer hold the soil together so it is eroded by wind and rain.

Flooding - evaporation from soil removes less water than transpiration, waterlogging encourages denitrification and soil loses nitrates.

Habitat loss reduces biodiversity.

Less photosynthesis means that less CO2 is removed from the atmosphere. CO2 is a ‘greenhouse gas’, increased CO2 leads to global warming and climate change.

Overfishing

Overfishing is where fish are caught at a higher rate than they reproduce and grow to the point where increased fishing efforts lead to declining catches.

Fish farming

Fish farming is where fish are intensively reared in ponds/tanks or nets; sea-fish are usually reared in large netted areas of the sea. This is one solution to over-fishing.

What is a planetary boundary

safe operating level for humanity that we must stay within. if exceeded there will be irreversible damage and global environmental change.

How does deforestation directly impact the planetary boundary for climate change

reduced co2 uptake via photosynthesis.

burning of felled trees puts co2 into the atmosphere

decay of waste tree material release co2 into the atmosphere

How can biodiversity loss be delayed via conservation methods

sperm and seed banks

minimum net mesh sizes so small fish can escape and reach maturity to reproduce

restrict habitat destruction like deforestation

having SSSI’s which are conserved

ecological impacts of fish farming

many fish in one small area leads to diseases passing through population quickly, can spread to wild fish

antibiotics used to keep fish stock healthy which can lead to development of antibiotic resistant bactera

farmed fish have selective advantage over wild fish so if escape, will outcompete and reduce genetic diversity

How does the use of nitrogen and phosphorus in fish farming impact the environment?

nitrogen in fish food lost as uneaten food, faeces or ammonia

EUTROPHICATION: extra N and P in water used by algae to grow, algal blooms block light to deeper aquatic plants so cannot p.s and die.

Decomposers(bacteria and fungi) decompose dead organic matter, aerobically respire using o2 in water.

fish and other plant have lack of 02 die. denitrifying bacteria reduce nitrates

why should you invert a test tube once to mix in dehydrogenase and yeast experiment with methylene blue, instead of shake

if shaken o2 would enter the test tube. methylene blue would remain blue

describe role of NAD in synthesis of ATP

NAD becomes reduced in glycolysis, link and Krebs

Delivers H atoms to ETC

Electrons released providing energy for H+ to be pumped into intermembrane space of mitochondria

Creates electrochemical gradient needed for ATP synthesis

If the inner membrane of mitochondria was permeable to protons, how would this affect respiration?

No proton gradient produced

No protons flow through stalked particles

No ATP produced so any energy released is lost as heat

Increased respiration rate

how do proteins enter respiration pathway

peptide bonds hydrolysed in proteins into amino acids which get deaminated

amino acids form keto acids and ammonia, where they are fed into glycolysis via pyruvate, or into the Krebs cycle via acetyl coA

how do lipids enter respiratory pathway

lipids are hydrolysed into fatty acids and glycerol via lipase.

Glycerol is converted into 3C triose phosphate

fatty acids are split into 2c acetate molecules and enter Krebs cycle as acetyl coA

3 ways the proton gradient is maintained in light dependent stage

The photolysis of water occurs in the thylakoid space releasing H+

protons are pumped into the thylakoid space using energy released from electrons travelling along ETC

removal of H+ in stroma by reduction of NADP as final electron acceptor

how does cyanide affect ETC in aerobic respiration

cyanide is a non-competitive inhibitor of the final carrier of the ETC

electrons and protons cannot be transferred to water

h+ and e- accumulate so the ETC does not function and the proton gradient is not maintained

ATP synthetase cannot produce ATP so cell dies.