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Edexcel iGCSE Biology 4BI1 - Paper 1B -Characteristics of living organisms- Exam Style Questions- New Syllabus

Edexcel International GCSE in Biology Paper 1B - All Chapters
Question

(a) All living organisms share characteristics.

(i) State two characteristics that all living organisms share.

(ii) Some organisms are pathogens. Which of these organisms can cause a bacterial disease in humans?

  • A. Chlorella
  • B. Lactobacillus bulgaricus
  • C. Mucor
  • D. Pneumococcus

(b) Viruses are pathogens but not living organisms.

(i) Describe the effect of a named virus that infects plants.

(ii) Give three differences between the structure of viruses and bacteria.

Most-appropriate topic codes (Edexcel IGCSE Biology):

• 1(a): Characteristics of living organisms — part (a)(i)
• 1(b): Variety of living organisms — part (a)(ii)
• 1(b): Pathogens (viruses, bacteria) — parts (b)(i), (b)(ii)
▶️ Answer/Explanation
Solution

(a)(i) Answer: Any two of: Nutrition, Respiration, Excretion, Sensitivity, Movement, Homeostasis, Reproduction, Growth.

Explanation: All living organisms share these eight characteristics, as outlined in Topic 1(a) of the specification.

(a)(ii) Answer: D (Pneumococcus)

Explanation: Pneumococcus is a bacterium that causes pneumonia. Chlorella is a protocyst, Lactobacillus is a beneficial bacterium, and Mucor is a fungus (Topic 1(b)).

(b)(i) Answer: Named Virus: Tobacco Mosaic Virus (TMV). Effect: Causes a mosaic pattern of discolouration on the leaves by damaging chloroplasts.

Explanation: TMV is a plant virus specified in Topic 1(b) that prevents chloroplast formation, leading to leaf discolouration.

(b)(ii) Answer: Any three of: 1. Viruses are smaller. 2. Viruses have a protein coat; bacteria have a cell wall. 3. Viruses lack cytoplasm and organelles; bacteria have them. 4. Viruses have either DNA or RNA; bacteria have both. 5. Viruses cannot reproduce independently; bacteria can.

Explanation: These structural and functional differences are covered in Topic 1(b), distinguishing viruses (non-living pathogens) from bacteria (living prokaryotes).

Question

Pollution of air or water can affect ecosystems.

(a) (i) Explain the biological consequences of air pollution by sulfur dioxide.

(a) (ii) State how sulfur dioxide pollution can be reduced.

(b) Some scientists have suggested that adding hydrogencarbonate solution to soil, instead of adding water, can increase plant growth.

Design an investigation to discover the effect that adding hydrogencarbonate solution has on the growth of seedlings.

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

Most-appropriate topic codes (Edexcel IGCSE Biology):

• 4(d): Human influences on the environment – air pollution by sulfur dioxide — parts (a)(i), (a)(ii)
• 1(c): Factors affecting the rate of photosynthesis – carbon dioxide concentration — part (b)
• 1(a): Characteristics of living organisms – growth — part (b)
▶️ Answer/Explanation
Solution

(a) (i)

Explanation: Sulfur dioxide (SO₂) released into the atmosphere, primarily from burning fossil fuels, has several harmful biological consequences. Firstly, it dissolves in atmospheric water vapour to form sulfuric acid (H₂SO₄), leading to acid rain. This acid rain can damage plant tissues, leading to deforestation, and can acidify lakes and rivers, causing the death of fish and other aquatic organisms. Furthermore, sulfur dioxide can cause breathing problems in humans and animals by irritating the respiratory system.

(a) (ii)

Answer: By reducing the burning of fossil fuels / using low-sulfur fuels / using alternative energy sources.

Explanation: The most direct way to reduce sulfur dioxide pollution is to decrease its production at the source. This can be achieved by burning less fossil fuel (like coal and oil), switching to low-sulfur varieties of these fuels, or using alternative energy sources that do not produce SO₂, such as solar, wind, or nuclear power.

(b)

Answer:

A suitable investigation would be designed as follows:

  • Control Variable (C): Use a large number of seedlings of the same species, age, and size. Divide them into groups. One group will be watered with a solution containing hydrogencarbonate (HCO₃⁻) at a specific concentration, while the control group will be watered with pure water. You could also test different concentrations of HCO₃⁻ to see the effect of the concentration.
  • Organism (O): Use the same species, age, and strain of seedling to ensure that any differences in growth are due to the treatment and not genetic variation.
  • Repeat (R): The experiment should be repeated for each concentration of hydrogencarbonate solution to ensure the results are reliable and not due to chance.
  • Measurement 1 (M1): The growth should be measured using a suitable metric, such as the yield (dry mass), height of the seedlings, number of leaves, or the number of plants that successfully germinate.
  • Measurement 2 (M2): These measurements should be taken after a stated, suitable period, for example, 48 hours or longer, to allow measurable growth to occur.
  • Standardization 1 (S1): Other factors that affect plant growth must be kept constant. This includes light intensity, carbon dioxide levels, and temperature.
  • Standardization 2 (S2): Further controls are needed, such as using the same type and volume of compost, the same volume of solution, and the same levels of humidity, moisture, and minerals/fertiliser for all seedlings.

Explanation: This experimental design is comprehensive. It starts by clearly defining the independent variable (presence and concentration of HCO₃⁻) and the dependent variable (a measure of growth). Using a large number of identical seedlings and repeating the experiment ensures reliability. Controlling all other variables (light, temperature, water volume, etc.) is crucial to ensure that any observed effect on growth can be confidently attributed to the hydrogencarbonate solution and not to other factors. Measuring growth after a set time allows for a fair comparison between the different treatment groups.

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