Identify the molecular or ecological energy transfer, use the relevant diagram or formula and connect limiting factors and human pressures to measured system outcomes.
The light-independent reactions of photosynthesis use the products of the light-dependent reactions to produce simple sugars.
Which row of the table shows the products of the light-dependent reactions that are used in the light-independent reactions?
ATP produced by
NADP
cyclic photophosphorylation
oxidised
cyclic photophosphorylation
reduced
non-cyclic photophosphorylation
oxidised
non-cyclic photophosphorylation
reduced
Simple sugars have the formula .
Name the inorganic molecule that provides each element in a simple sugar. (2)
Two types of plant, and , have slightly different pathways of light-independent reactions.
The graph shows how the rate of photosynthesis is affected by temperature in these two types of plant.
Rate of photosynthesis / a.u.
Describe three conclusions that can be made about the differences in the effect of temperature on the rate of photosynthesis in these two types of plant.
Calculate the for the enzymes in plants.
Use the formula:
where is the initial rate of reaction at .
Give your answer as a whole number.
Photosynthesis consists of the light-dependent reactions and the light-independent reactions.
In the light-dependent reactions, light energy is converted into energy stored in ATP.
Explain why light energy is converted into energy stored in ATP.
An equation can summarise the production and breakdown of ATP.
Complete this equation, by writing the names of the substrates and the type of reaction on the three dotted lines provided. +
phosphorylation
Explain the role of light energy in the light-dependent reactions.
The light-independent reactions use products of the light-dependent reactions to produce simple sugars.
Which row of the table shows the products of the light-dependent reactions that are used in the light-independent reactions?
(b) The light-independent reactions use products of the light-dependent reactions to produce simple sugars.
ATP produced by
NADP
cyclic photophosphorylation
oxidised
cyclic photophosphorylation
reduced
non-cyclic photophosphorylation
oxidised
non-cyclic photophosphorylation
reduced
Simple sugars have the formula .
Name the inorganic molecule from which each element in a simple sugar originated.
C
H
O
Simple sugars are used in the synthesis of new biological molecules.
Which row of the table shows the inorganic ions that are needed to synthesise these new biological molecules?
Chloroplasts are involved in both the light-dependent reactions and light-independent reactions of photosynthesis.
Which row of the table shows where the light-dependent reactions and light-independent reactions take place?
□ A
□ B
The diagram shows the outline of a chloroplast.
Draw three labelled features on this diagram that are found in a chloroplast, other than the stroma and the thylakoid membranes.
□ C
□ D
.
An absorption spectrum shows how much light is absorbed by chloroplasts at different wavelengths of light.
The table shows the colour of light at four wavelengths.
Which wavelength of light is absorbed the least by chloroplasts?
□ A 460 nm
□ B 520 nm
□ C 600 nm
□ D 680 nm
State what is meant by the term action spectrum.
Chloroplast pigments can be separated and then identified by their Rf values.
Which process can be used to separate chloroplast pigments?
chromatography
dendrochronology
osmosis
PCR
The diagram shows separated chloroplast pigments, J and K.
What is the Rf value for chloroplast pigment J ?
□ A 0.625
□ B 0.800
□ C 0.830
□ D 1.714
The light-independent reactions of photosynthesis use the products of the light-dependent reactions to produce simple sugars.
Simple sugars have the formula .
Name the inorganic molecule that provides each element in a simple sugar. (2)
The light-independent reactions of photosynthesis use the products of the light-dependent reactions to produce simple sugars.
Which row of the table shows the products of the light-dependent reactions that are used in the light-independent reactions?
ATP produced by
NADP
cyclic photophosphorylation
oxidised
cyclic photophosphorylation
reduced
non-cyclic photophosphorylation
oxidised
non-cyclic photophosphorylation
reduced
The photograph shows an aquatic plant, Cabomba aquatica.
(Source: © Dorling Kindersley Ltd / Alamy Stock Photo)
This plant grows in water in Asia.
A student observed that the shortest plants were always seen in water shaded by overhanging trees. The student thought that reduced photosynthesis may be limiting the growth of these plants.
The student formed the following hypothesis:
Low light intensity reduces the rate of photosynthesis in Cabomba aquatica.
Plan an investigation to find evidence to support or reject this hypothesis.
Your answer should give details under the following headings.
Devise a detailed method, including how you would control and monitor important variables.
Stages of succession can be seen on different parts of a sand dune system.
The greater the distance of the sand dune from the sea, the later the stage of succession.
The diagram shows a sand dune system and the table gives some information about the different types of sand dune in this system.
Sand dunes can be classified as fixed dunes, semi-fixed dunes and shifting dunes.
The graph shows the mean net primary productivity (NPP) above the ground and below the ground for these three types of sand dune.
Describe the conclusions that can be drawn from this graph.
Explain how the products of the light-independent reactions become NPP below the ground.
Lions, giraffes and acacia trees are found on the African Plains.
The diagram shows the energy in the trophic levels that these organisms occupy.
Calculate the efficiency of energy transfer between trophic level one and trophic level two.
The diagram shows some processes linking photosynthesis to productivity and the distribution of biomass in the trees in a forest.
Forests are examples of ecosystems. State what is meant by the term ecosystem.
The photograph shows part of a desert in Mexico.
(Source: © Alexander Semkin/Alamy Stock Photo)
A scientist observed that one species of cactus, Neobuxbaumia tetetzo, was often found near a species of tree, Mimosa luisana.
The scientist decided to test the hypothesis that the cactus plants often grow close to mimosa trees.
One hundred locations were selected at random. A quadrat was placed at each location.
The presence or absence of each species was recorded in each quadrat.
Abiotic variables in the soil cannot be controlled in this investigation. However, these variables can be measured to confirm that these plants are growing in similar conditions.
Choose one of the variables you have identified in (i).
State the effect it could have on the results if the measured values were not similar.
Variable
The effect it could have on the results if the values were not similar.
Lions, giraffes and acacia trees are found on the African Plains.
The diagram shows the energy in the trophic levels that these organisms occupy.
Give the meaning of each of the following terms, using the information in the diagram to illustrate your answer.
Niche
The photograph shows part of a desert in Mexico.
(Source: © Alexander Semkin/Alamy Stock Photo)
A scientist observed that one species of cactus, Neobuxbaumia tetetzo, was often found near a species of tree, Mimosa luisana.
The scientist decided to test the hypothesis that the cactus plants often grow close to mimosa trees.
One hundred locations were selected at random. A quadrat was placed at each location.
The presence or absence of each species was recorded in each quadrat.
Abiotic variables in the soil cannot be controlled in this investigation. However, these variables can be measured to confirm that these plants are growing in similar conditions.
State two abiotic variables in the soil that could affect this investigation.
First variable
Second variable
Stages of succession can be seen on different parts of a sand dune system.
The greater the distance of the sand dune from the sea, the later the stage of succession.
The diagram shows a sand dune system and the table gives some information about the different types of sand dune in this system.
Explain the changes in these sand dunes with distance from the sea.
Use the information in the table to support your answer.
The graph shows the changes in mean temperature of the surface of the Earth from 1970 to 2017.
Change in mean temperature of the surface of the Earth/
Studying the width of tree rings provides evidence for climate change.
Which of the following involves the study of tree rings?
dendrochronology
entomology
epigenetics
proteomics
Explain why the width of tree rings produced in 1970 would be different from the width of tree rings produced in 2010.
The diagram shows part of the carbon cycle.
Key
The numbers in smooth brackets ( ) show the mass of carbon in petagrams found in either the atmosphere, plants or surface ocean.
The numbers in square brackets [ ] show the mass of carbon in petagrams transferred between the atmosphere and the plants or surface ocean per year.
A petagram is equal to grams.
Anthropogenic climate change is a result of an increase in the mass of carbon in the atmosphere.
State what is meant by the term anthropogenic climate change.
The diagram shows part of the carbon cycle.
Key
The numbers in smooth brackets ( ) show the mass of carbon in petagrams found in either the atmosphere, plants or surface ocean.
The numbers in square brackets [ ] show the mass of carbon in petagrams transferred between the atmosphere and the plants or surface ocean per year.
A petagram is equal to grams.
The mass of carbon recycling between the atmosphere and the plants, and the atmosphere and the oceans, are roughly balanced.
State how carbon is exchanged between the atmosphere and the oceans.
Anthropogenic climate change is a result of an increase in the mass of carbon in the atmosphere.
Explain one way in which the effects of anthropogenic climate change can be reduced.
The graph shows the changes in mean temperature of the surface of the Earth from 1970 to 2017.
Change in mean temperature of the surface of the Earth/
What is the estimated change in the mean temperature of the surface of the Earth in 2030?
1.3
1.1
0.8
0.2
The photograph shows a young locust eating the leaves of a plant.
(Source: © Nigel Cattlin / Alamy Stock Photo)
Locusts can breed in large numbers and destroy crops, such as sorghum, in East Africa.
A scientist observed that some varieties of sorghum were more likely to be eaten by young locusts.
The scientist collected the seeds of two varieties of sorghum (A and B) and grew them in trays. Locust eggs were collected and hatched into young locusts.
Twenty young locusts were placed in a cage containing 100 g of fresh sorghum leaves of variety A. The cage was kept at .
After 24 hours, the leaves were removed and the mass of leaves eaten was calculated.
This method was repeated with fresh sorghum leaves of variety B. The method was repeated six times for these two varieties of sorghum leaves.
The results:
Mass of leaves eaten of variety A 17.3 17.2 17.5 17.0 16.7 16.9
Mass of leaves eaten of variety B 17.8 17.9 17.7 17.6 17.8 17.4
Some scientists predict that climate change will increase the destruction of crops in East Africa.
Suggest one reason why some scientists think this.
Quince are fruit that grow on trees.
When a quince falls from the tree, two processes take place: browning and decomposition.
Browning takes place when the fruit is cut and exposed to the air. The browning is catalysed by the enzyme polyphenol oxidase (PPO).
The photographs show browning in a quince cut in half.
Freshly-cut quince showing some browning
Cut quince exposed to the air showing extensive browning
Activity of the enzyme PPO at different temperatures was investigated.
The graph shows the results of this investigation.
Sketch the graph for enzyme activity plotted against temperature for this enzyme.
Use the data from this investigation.
Calculate the for this enzyme, using the data from this investigation, shown in the first graph.
Use the formula
where is the initial rate of reaction at
and is the initial rate of reaction at .
Aquaculture is the controlled cultivation of aquatic organisms such as fish, shellfish and plants. It is an important source of food in many countries of the world. The photograph shows freshwater aquaculture ponds in Africa.
(Source: © E.Westmacott/Alamy Stock Photo)
Vibrio are bacteria that are common in aquatic habitats. They cause diarrhoea and cholera and are also pathogenic to shellfish. The resistance of Vibrio to antibiotics and to heavy metals in aquaculture ponds in Nigeria was investigated.
The samples of Vibrio taken from each pond were spread on agar containing different antibiotics.
The scientists expected the percentage of resistant bacteria to be higher in the samples of Vibrio taken from the ponds previously treated with antibiotics. Explain why the scientists expected this difference.
Madagascar is a large island off the southeast coast of mainland Africa.
Lemurs are endemic to Madagascar.
There are many different species of lemur, all of which evolved from one common ancestor. This common ancestor is thought to be a primate that was carried across the sea from mainland Africa on a raft of vegetation.
The photographs show two different species of lemur, Sifaka and Indri, found in the same region of Madagascar.
Sifaka
Indri
The diet of Sifakas is mostly seeds but also includes fruits, flowers and some types of leaves. The diet of Indri is mainly leaves.
Explain the types of speciation that have taken place in the evolution of Sifakas and Indri in this region of Madagascar.
There has been an increase in the number of forest fires in many areas of the world.
Climate change caused by humans is claimed to be responsible for this.
The photograph shows the devastation caused by a forest fire in Myanmar.
Explain why some people consider this claim to be controversial.
There has been an increase in the number of forest fires in many areas of the world.
Climate change caused by humans is claimed to be responsible for this.
The photograph shows the devastation caused by a forest fire in Myanmar.
Reforestation is one way to repair the damage caused to forests by climate change.
Explain why the changes to the environment caused by climate change need to be considered when selecting the species of trees to use in reforestation.
(4)