T5 - On the wild side

Question 1

What is dendrochronology

Answer 1

The use of tree rings to work out data about the tree and its environment which can be used for analysing changes in climate conditions.

Question 2

Gross primary productivity

Answer 2

The total amount of energy fixed as chemical energy during photosynthesis carried out by producers.

Question 3

Net primary productivity

Answer 3

The amount of chemical energy that is available for transfer once the amount of energy loss from respiration is deducted from the total amount of energy.

Question 4

Equation for NPP

Answer 4

NPP = GPP - energy lost from respiration

Question 5

Pioneer species

Answer 5

• The first species to occupy a new area.
• Adapted to survive harsh conditions
• E.g. lichens and moss

Question 6

What is an ecosystem

Answer 6

A community of living organisms and their physical environment in an area which is self-sustaining.

Question 7

Energy lost at each trophic level can be due to

Answer 7

• Undigested matter
• Respiration (thermal energy transfer to the surroundings)
• Waste products like urea

Question 8

When to use systematic sampling

Answer 8

• When there are environmental gradients
• Like light, temp, humidity or woodland and sand
• Which can be measured at intervals along a transect

Question 9

When to use random sampling

Answer 9

• If two areas appear to be different and need to be compared.
• Quadrats are placed in a grid using random numbers.

Question 10

What are the 4 evidences of climate change

Answer 10

1. Records or carbon dioxide levels - increasing
2. Temperature records - increasing slightly
3. Pollen in peat bogs - pollen grain analysis can show the environment when plants were present
4. Dendrochronology - size of tree rings is affected by temperature.

Question 11

How are predictions of climate change made

Answer 11

• Extrapolation of data
• Used in models of future climate change
• However they do not include factors like human efforts for the reduction in emissions of greenhouse gases.

Question 12

Light-dependent reaction in thylakoid membrane

Answer 12

1. Energy from light (photons) travels through pigments in photosystem II to the primary pigment reaction centre.
2. An electron (from the photolysis of water) gets to a higher energy state and is now ‘excited’.
3. The excited electron leaves photosystem II and travels through the electron transport chain (ETC) to photosystem I, losing energy on the way.
4. Energy lost by the electron allow H+ ions to move from the stroma into the thylakoid. Creating an electrochemical gradient.
5. Because of the imbalance of charge in and out of the thylakoid, H+ ions leave the thylakoid by facilitated diffusion through ATP synthase. This is called chemiosmosis.
6. For H+ ions to move out through ATP synthase:
   ADP + Pi –> ATP
   This is called photophosphorylation.
7. The excited electron in photosystem I reacts with H+ ions to create H. Which then reacts with NADP+ to form NADPH in a reduction reaction.
8. Oxygen from the splitting of water is lost as a waste product.

Question 13

Light-independent reaction in the stroma

Answer 13

1. Carbon dioxide is ‘fixed’ – it combines with 5 carbon RuBP using enzyme RUBISCO
2. The unstable 6-carbon intermediate compound formed by the previous reaction breaks down into 2 glycerate 3-phosphate (GP) (2 x 3C)
3. ATP and NADPH are used to reduce 2 GP molecules into GALP (2 x 3C)
4. 1 in 6 GALP molecules are used to make glucose, which is then used to make organic compounds like polysaccharides, lipids, amino acids and nucleic acid.
5. ATP is used to regenerate RuBP from the remaining 5 carbons from GALP.
6. To form one whole glucose molecule (6C) the calvin cycle has to repeat 6 times.

Question 14

What is genetic drift

Answer 14

Random changes in allele frequency

Question 15

What is gene flow (migration)

Answer 15

Gene from one population is in another population. Mixing of gene pools.