Classification

Tansy, Tanacetum vulgare, is a plant that grows in dense patches. The tansy beetle, Chrysolina graminis, feeds on, and completes its life cycle on T. vulgare.

C. graminis is 8–10 mm long and green in colour.

Two other green beetles can also be found in the same habitat.

• The dock beetle, Gastrophysa viridula, which is 4–7 mm long.

• The mint leaf beetle, Chrysolina herbacea, which is 6–10 mm long.

Figure 2 shows the life cycle of C. graminis.

How many different genera of beetles are there in the information provided?

Ecologists investigated the population size of C. graminis using the

mark-release-recapture method.

Table 2 shows the ecologists’ results.

The ecologists captured and marked the first sample of beetles during the second week of August. They identified the species of beetle before marking them.

Use the information provided to suggest:

two reasons why the first sample of beetles was captured during the second week of August

one reason why the beetles had to be identified before being marked.

Use the data provided in Table 2 to estimate the population size of C. graminis.

Show your working.

The ecologists repeated the investigation over a five–year period to monitor the population size of C. graminis.

State two precautions they would have taken each year to obtain comparable data.

Courtship behaviour in the frog species, Xenopus laevis, involves male frogs calling to:

• attract sexually active females – these are advertisement calls

• start and continue mating – these are mating calls

• signal when a male is not sexually active – these are rasping calls.

Scientists investigated frog courtship behaviour by feeding a population of sexually active male frogs a diet containing the hormone EE2. The scientists also fed a separate control population of sexually active male frogs a diet without EE2.

They determined the percentage of males making advertisement calls or rasping calls in each population.

Table 6 shows their results.

There were 800 males in the control population.

Each male made one type of call.

Use this information and Table 6 to calculate the number of males making mating calls in the control population.

Suggest one change the scientists could make to both frog populations to increase the number of mating calls.

The scientists also investigated the effect on female frog courtship behaviour of feeding EE2 to male frogs.

Table 7 shows their results.

EE2 is contained in human contraceptive pills. Some EE2 is released in human urine and collects in sewage. Untreated sewage pollutes the water in frog habitats.

Suggest and explain the effect EE2 pollution in frog habitats will have on frog breeding.

Use information from Table 6 and Table 7 in your answer.

Effect on frog breeding

The human disease, malaria, is caused by infection with a single-celled eukaryotic organism.

Figure 2 shows a diagram of Plasmodium vivax, one of the species that can cause malaria.

Other than the Golgi apparatus, name one structure in Figure 2 which shows that P. vivax is a eukaryote.

Describe two functions of the Golgi apparatus in a eukaryotic cell.

P. vivax evolved from a common ancestor in Africa. As humans migrated around the world, new strains of P. vivax evolved.

P. vivax is now extremely rare in Africa but there are several different strains of P. vivax in other parts of the world.

Figure 3 shows a phylogenetic diagram of the evolution of these different strains.

What does Figure 3 suggest is the order of human migration out of Africa?

Tick (✓) one box.

There are an estimated 229 million cases of human malaria worldwide per year. 94% of these cases are found in Africa, but are not caused by P. vivax. P. vivax does cause 61% of the cases of human malaria outside Africa.

Use this information to calculate the number of cases worldwide caused by P. vivax each year.

In Africa today, most of the human population are resistant to malaria caused by P. vivax.

Use your knowledge of natural selection to explain why this resistance is so common in Africa.

Define genome and proteome.

The classification system used in the early 20th century grouped different species of bacteria according to the position and shape of flagella on bacterial cells and by the number of flagella per cell. These were observed using an optical microscope. Each species of bacterium has a characteristic cell shape and arrangement of flagella. These characteristics may be shared with other species within a genus. Flagella are fragile, difficult to stain and may extend from the cell at any angle.

Consider the accuracy and limitations of the early classification of bacteria using the arrangement of flagella.

Suggest why several bacterial species have been renamed in recent years.

Figure 6 shows an image from an optical microscope of a single bacterial cell.

This bacterial cell is 2.3 μm long (excluding the flagellum).

Calculate the magnification of this image.

Show your working.

Scientists investigated the effect of full sun and shade on the rate of photosynthesis in a species of shade-tolerant tree.

To estimate the rate of photosynthesis, the scientists measured uptake of carbon dioxide by trees in a forest. They measured uptake of carbon dioxide during two parts of the day:

• 08.30 – 09.40 hours

• 11.40 – 13.15 hours.

Figure 8 shows the scientists’ results.

Figure 8

Figure 8 not reproduced here due to third-party copyright restrictions

Calculate the total uptake of carbon dioxide between 11.40 and 13.15 hours in trees exposed to full sun in a forest that is 12 000 m² in area.

Give your answer in standard form. Show your working.

Figure 8 shows there is a small difference in the mean uptake of carbon dioxide between 08.30 and 09.40 hours by trees in full sun and by trees in the shade. When the scientists performed a statistical test on these data, they calculated P > 0.5

State what this P value tells you about this difference.

Explain your answer using the words probability and chance.

In this species of tree, very high light intensities can inhibit the release of electrons from chlorophyll.

Suggest how this could explain the results shown in Figure 8 for 11.40 to 13.15 hours.

Tomato plants grow best in high light intensities. To increase the yield of tomato plants, a farmer uses LED lightbulbs to provide additional light.

The increase in dry mass (D) produced when using additional light can be calculated using this equation.

Where L = light used in photosynthesis F = GPP to NPP conversion factor for tomato plants

Table 5 shows some of these values for LED lightbulbs.

Use the equation and Table 5 to calculate the increase in dry mass produced when using LED lightbulbs.

Give your answer in standard form and give the units.

Mature leaves from slow-growing, shade-tolerant plants produce poisonous chemicals that are a defence against being eaten by herbivores.

Suggest how this benefits slow-growing, shade-tolerant plants.

Scientists measured the concentration of poisonous chemicals produced by

shade-tolerant plant species in six taxa. They compared this with the mean concentration of poisonous chemicals produced by all plants and the phylogenetic relationships between the six taxa.

Figure 9 shows the scientists’ results.

A journalist published the following summary of these results.

‘The more recently a shade-tolerant plant species evolved, the greater the concentration of poisonous chemicals it produces.’

Do the data in Figure 9 support this summary? Justify your answer.

Describe how a triglyceride molecule is formed.

Table 5 shows some properties of four fatty acids.

Figure 10 shows diagrams of these fatty acids.

Put a tick () in one box that contains correct information about one of these fatty acids.

The percentage of saturated fatty acids compared with unsaturated fatty acids found in lipid stores in seeds differs in different populations.

Scientists investigated two populations of the plant, Helianthus annuus.

The scientists grew young plants from seeds collected from each population. They placed the seeds on wet tissue paper so that the root growth was visible.

They grew seeds from each population at two temperatures:

• warm temperature of 24 °C

• cool temperature of 10 °C

After 10 days, the scientists measured the length of each root.

Table 6 shows some of the properties of the two populations and the scientists’ results.

The mean ±2 × standard deviation includes 95% of the data.

The scientists used a data logger to measure the length of the root rather than a ruler.

Suggest one reason why they used a data logger and explain why this was important in this investigation.

It is known that:

• during respiration saturated fatty acids yield more energy than unsaturated fatty acids

• saturated fatty acids have higher melting points than unsaturated fatty acids

• lipases in seeds act more rapidly on liquid substrates.

Use this information and Table 6 to show how each population is better adapted for its natural environment when compared with the other population.

Although these two populations are completely separate and show genetic variation, they are both called Helianthus annuus.

Explain why they are both given this name.

Ulva lactuca is an alga that lives on rocks on the seashore. It is regularly covered by seawater.

Figure 6 shows a diagram of one Ulva lactuca alga.

Unlike plants, Ulva lactuca does not have xylem tissue.

Suggest how Ulva lactuca is able to survive without xylem tissue.

Ulva lactuca has a haploid and a diploid form.

Figure 7 shows the life cycle of Ulva lactuca.

On Figure 7 complete each box with an appropriate letter to show the type of cell division happening between each stage in the life cycle. Use ‘ T ’ to represent mitosis and ‘ E ’ to represent meiosis.

Ulva prolifera also produces haploid, mobile single cells that can fuse to form a zygote.

Suggest and explain one reason why successful reproduction between Ulva prolifera and Ulva lactuca does not happen.

Bees are flying insects that feed on nectar made in flowers. There are many different species of bee.

Scientists investigated how biodiversity of bees varied in three different habitats during a year. They collected bees from eight sites of each habitat four times per year for three years.

The scientists’ results are shown in Figure 4 in the form they presented them.

What is meant by ‘species richness’?

From the data in Figure 4, a student made the following conclusions.

1. The natural habitat is most favourable for bees.

2. The town is the least favourable for bees.

Do the data in Figure 4 support these conclusions? Explain your answer.

1. The natural habitat is most favourable for bees.

2. The town is the least favourable for bees.

The scientists collected bees using a method that was ethical and allowed them to identify accurately the species to which each belonged.

In each case, suggest one consideration the scientists had taken into account to make sure their method

2. allowed them to identify accurately the species to which each belonged.

Suggest and explain two ways in which the scientists could have improved the method used for data collection in this investigation.

Three of the bee species collected in the farmland areas were Peponapis pruinosa, Andrena chlorogaster and Andrena piperi.

What do these names suggest about the evolutionary relationships between these bee species? Explain your answer.

Figure 3 shows two different ways of classifying the same three species of snake.

Classification X is based on the frequency of observable characteristics

Classification Y is based on other comparisons of genetic characteristics.

All three species of snake belong to the Python family.

What do these classifications suggest about the evolutionary relationships between these species of snake?

Complete Table 4 below to show the missing names of the taxa when classifying these snakes.

There is a debate about the name of one of these species of snake. Some scientists name it Liasis papuana and other scientists name it Apodora papuana.

Give the name of the taxon about which the scientists disagree.

State three comparisons of genetic diversity that the scientists used in order to generate Classification Y.