The Nature & Variety of Living OrganismsEdexcel IGCSE Biology: Topic test

20 questions, 54 marks

Edexcel IGCSE Biology

The Nature & Variety of Living Organisms topic test

Total 54 marks

Name

Class

Date

1
A microbiologist takes a water sample from a garden pond and examines it under a microscope. On the slide she sees a single-celled amoeba moving across the field of view and engulfing a smaller organism, and separately, filaments of a mould growing on a piece of submerged wood.
(a)
Which kingdom does the amoeba belong to?
[1 mark]
AFungi
BProtoctista
CProkaryotae
DAnimalia
(b)
Which feature identifies the mould filaments as fungal rather than plant material?
[1 mark]
AThe presence of a cell wall
BThe presence of a nucleus
CThe absence of chlorophyll, so it cannot photosynthesise
DIts ability to reproduce
(c)
Besides growth, describe two other characteristics of living organisms that both the amoeba and the mould must show.
[2 marks]
Total for question 1: 4 marks
2
A student compares a sample of Salmonella bacteria, cultured on agar in a laboratory, with a sample of the virus that causes the common cold. Both are far too small to see with the naked eye.
(a)
Which of these structures is found in the bacterium but is absent from the virus?
[1 mark]
AGenetic material
BA protein coat
CNothing — the two are structurally identical
DCytoplasm
(b)
Why is the cold virus not classified as a living organism?
[1 mark]
AIt cannot reproduce independently, only inside a host cell
BIt does not contain genetic material
CIt is too small to observe with the naked eye
DIt causes disease
(c)
State two structural features of the bacterial cell that are not found in the virus.
[2 marks]
Total for question 2: 4 marks
3
A student is given a fast-growing crystal placed in a supersaturated solution, and a sample of yeast placed in a warm, sugary solution, and is asked to use the characteristics of living organisms to decide whether each counts as living.
(a)
Explain why the crystal, despite increasing in size, is not classed as a living organism.
[3 marks]
(b)
The yeast sample is observed to increase in cell number and to release bubbles of gas. Explain how this shows that the yeast is a living organism, referring to three characteristics of living organisms.
[4 marks]
Total for question 3: 7 marks
4
A food safety officer investigates an outbreak of illness traced to a batch of soft cheese, found to be contaminated with both a bacterial pathogen and a fungal pathogen. In the public health advice issued afterwards, the officer explains why viruses are treated differently from these other microorganisms.
(a)
Describe the key structural differences between a typical bacterial cell and a typical fungal cell, such as those responsible for the contamination.
[6 marks]
(b)
Explain why viruses are treated differently from bacteria and fungi in the health advice, describing their structure and how they cause disease.
[6 marks]
Total for question 4: 12 marks
5
A gardener notices lichen, a partnership between a fungus and an alga, growing on a stone wall, and wants to know whether it shows the characteristics of a living organism.
(a)
Which characteristic of living organisms is the lichen displaying when it slowly increases in size over several years?
[1 mark]
AExcretion
BGrowth
CMovement
DReproduction
(b)
The algal partner converts light energy into chemical energy stored in sugars. Which characteristic of living organisms is this an example of?
[1 mark]
AMovement
BExcretion
CNutrition
DGrowth
(c)
Besides growth and nutrition, describe two other characteristics of living organisms the gardener would need to observe before concluding the lichen shows all eight characteristics of life.
[2 marks]
Total for question 5: 4 marks
6
A doctor is treating a patient with two separate infections at once: one caused by Plasmodium, a single-celled protoctist that lives inside red blood cells, and one caused by a strain of the bacterium that causes tuberculosis.
(a)
Plasmodium is classified as a protoctist rather than a prokaryote mainly because it
[1 mark]
Ahas a cell wall
Bis single-celled
Ccan move
Dhas a nucleus enclosing its genetic material
(b)
Which feature of the tuberculosis bacterium would NOT be found in a Plasmodium cell?
[1 mark]
AA circular chromosome of DNA free in the cytoplasm
BA cell membrane
CCytoplasm
DRibosomes
(c)
State two structural features that classify Plasmodium as a eukaryotic organism, unlike the tuberculosis bacterium.
[2 marks]
Total for question 6: 4 marks
7
A microbiology student is given four unlabelled samples to classify using only their characteristics: the influenza virus, a culture of Salmonella bacteria, a mould growing on bread (a fungus), and a single-celled Amoeba (a protoctist). The student must identify the odd one out and explain the structural differences between the other three.
(a)
Explain why the influenza virus is the odd one out among the four samples, in terms of whether it is classed as a living organism.
[3 marks]
(b)
Describe one key structural feature that distinguishes each of the three living samples — the bacterium, the fungus and the protoctist — from one another.
[4 marks]
Total for question 7: 7 marks
8
A science museum exhibit compares four specimens to teach visitors about the diversity of life: a preserved mushroom (fungus), a sample of pond algae (protoctist), a colony of Streptococcus bacteria, and a set of bacteriophage viruses that infect the bacteria. Visitors are asked to classify each specimen and explain their reasoning.
(a)
Compare the cell structure of the fungus, the algae and the bacteria, describing one similarity and explaining the key differences between the eukaryotic organisms and the prokaryotic organism.
[6 marks]
(b)
Explain why the bacteriophage viruses infecting the bacteria are not classed as living organisms, and describe how they reproduce inside a bacterial host cell.
[6 marks]
Total for question 8: 12 marks

End of questions