Edexcel IGCSE Biology Biology Paper 1 November 2020 question paper 4BI1/1B

The bacterium H. pylori causes stomach ulcers.

The diagram shows this bacterium.

Which of these is found in this bacterium?

The bacterium has evolved to release an enzyme called urease.

The action of the bacterium neutralises the acid in the stomach.

What is the pH changed to?

Use the theory of evolution by natural selection to explain how H. pylori bacteria could have evolved to produce urease.

Probiotics are live microorganisms that can have health benefits when consumed.

Scientists investigate the ability of probiotics and cranberry juice to reduce the growth of H. pylori.

The scientists give various treatments to a group of people who have H. pylori.

The treatments are given daily for three weeks.

The scientists measure the mean percentage reduction of H. pylori for each treatment.

The table shows the scientists’ results.

Give two conclusions from these results.

The passage describes reproduction in flowering plants.

Complete the passage by writing a suitable word in each blank space.

Flowers are organs that allow plants to carry out_........ reproduction.

The male gamete is contained within the_........ grains. These grains

are released from the_........ , which is found on top of the filament.

These grains need to land on the_........ , the female part of the flower.

Grains can be transferred by wind or by animals. These animals are often insects such as

_........ or butterflies. The petals of insect-pollinated plants are often

_........ and brightly coloured. After pollination, the grains

germinate and a tube grows down the_........ to reach the ovary.

In the ovary, the gametes fuse. This process is known as_........ .

A student uses a light microscope to look at a human cheek cell.

The student makes this drawing of the cell.

Name the organelle shown in the drawing.

Mitochondria are organelles that are too small to be seen using a light microscope.

The drawing shows a mitochondrion that has been magnified.

The actual length of this mitochondrion is 6 µ m.

[1 µ m = 0.001 mm]

Calculate the magnification of this drawing.

The table gives information about mitochondria in different human cells.

What is the mean number of mitochondria per µm³ in a heart muscle cell?

Comment on the differences in the data for the sperm and for the egg.

The diagram shows a food chain in the Antarctic ocean.

Which term describes the trophic level of the krill?

Draw a labelled pyramid of biomass to represent this food chain.

The microscopic plants float in seawater, but also grow on the lower surface of ice.

The krill feed on the microscopic plants.

They remove microscopic plants from the lower surface of the ice at a rate of 1.6 cm² per second.

Calculate the time taken for the krill to remove microscopic plants from one square metre of ice.

Give your answer in minutes.

time taken =_........ minutes

A student investigates the rate that krill feeding removes microscopic plants floating in seawater.

Suggest how the student could do this investigation in a laboratory.

Krill obtain most of their food from microscopic plants growing on the lower surface of ice.

Explain how global warming could affect the whale population in the Antarctic ocean.

Plants can be genetically modified (GM) to produce insect poison.

They are modified using a bacterium called Agrobacterium.

This bacterium has a plasmid that contains recombinant DNA.

Describe how the plasmid is modified to contain recombinant DNA.

A farmer can use either of these methods to improve his crop yield.

● grow GM plants that produce the insect poison

● grow non-GM plants and use pesticides

The farmer decides to grow the GM plants rather than using pesticides.

Discuss the decision made by the farmer.

Aerobic respiration is a process in living organisms.

Which of these is the balanced chemical symbol equation for aerobic respiration?

A student uses this apparatus to investigate aerobic respiration in a locust.

The coloured water drop moves during the investigation.

Explain why the coloured water drop moves during the investigation.

The student compares the aerobic respiration of male and female locusts.

He uses three male locusts and three female locusts.

He uses locusts of the same age and the same species.

Explain three other variables that the student needs to control.

The table shows the student’s results.

Complete the table by giving the missing mean value.

Comment on the reliability of the data in the table.

The table gives the masses of protein and lipid (fat) in the same volume of milk from a cow and from a human.

Describe how you would test a sample of cow’s milk and a sample of human milk to show they contain different masses of protein.

Some of the proteins in milk are antibodies.

Explain why antibodies in milk are useful for babies.

Give two ways that lipid in milk is used by babies.

Milk is used to make yoghurt.

Name the carbohydrate in milk used to make yoghurt.

Name the bacteria added to milk to make yoghurt.

Explain why milk needs to be heated to a high temperature at the start of the process for making yoghurt.

Cell division can be by meiosis or by mitosis.

Where are cells dividing by meiosis found in a human?

Which part of a flowering plant is usually used to demonstrate cells dividing by mitosis?

The table lists features comparing the processes of meiosis and mitosis in human cells.

Complete the table by giving the missing information.

Cell division can cause variation in offspring.

Describe other causes of variation in offspring.

Scientists investigating a drug treatment use rats that are homozygous for many genes.

Suggest the advantages of using rats that are homozygous for many genes.

The table shows the production of wheat and barley in the United Kingdom from 2011 to 2015.

Plot a line graph to show the changes in wheat and barley production from 2011 to 2015.

Use a ruler to join the points with straight lines.

Describe the changes in the production of each crop from 2011 to 2015.

Determine which of the crops had the greatest percentage change in production from 2011 to 2015.

Show your working.

A wheat field, 100 m by 100 m, can produce a total yield of 25 000 kg of carbohydrate in a year.

Calculate the mean mass, in grams, of carbohydrate produced each day by a square metre of the wheat field.

The diagram shows three types of neurone.

Give the names of these neurones.

Explain the role of these neurones in the withdrawal reflex of a finger from a hot object.

A teacher uses this method to estimate the speed of a nerve impulse.

● students stand in a circle and hold hands

● student A in the circle starts a timer and at the same time squeezes the hand of student B on his left

● when student B feels his hand being squeezed, he immediately squeezes the hand of the student on his left

● this process continues around the circle of students until student A feels his hand being squeezed and he stops the timer

Explain what other measurements the teacher would need to make in order to calculate the speed of a nerve impulse.

Describe whether the teacher’s method is likely to give an accurate estimate of the speed of a nerve impulse.

Some cosmetic companies claim that adding argan oil to their shampoo increases the strength of human hair.

Design an investigation to find out if argan oil shampoo does increase the strength of human hair.

Include experimental details in your answer and write in full sentences.