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8th grade cells, genetics and evolution

8th grade (Year 9 in England) · 14 questions · Common Core: NGSS.MS-LS3-1, NGSS.HS-LS1-1, NGSS.HS-LS3-1, NGSS.HS-LS1-3 · England: KS3 Biology: Genetics and evolution, KS4 Combined Science: Evolution, inheritance and variation, GCSE Combined Science: Cell biology (required practical: osmosis)

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Date

Score/ 14

1
Question 1
Why are identical twins so useful in studying variation?
- A. They have the same genes, so differences must be environmental
- B. They never vary at all
- C. They have no genes
- D. They always live in the same house
2
Question 2
How many chromosomes are in a normal human body cell?
- A. 23
- B. 12
- C. 46 (23 pairs)
- D. 92
3
Question 3
Which word means: the characteristic you can see, such as brown fur?
- A. recessive
- B. dominant
- C. phenotype
- D. allele
4
Question 4
A poison stops respiration in root cells. Which process stops first?
- A. osmosis of water
- B. diffusion of oxygen
- C. active transport of mineral ions
- D. all three equally
5
Question 5
Transport in cells: which statement is true?
- A. Osmosis needs energy from respiration.
- B. Active transport can move substances from a low to a high concentration.
- C. Water moves by osmosis from a concentrated to a dilute solution.
- D. Active transport only happens in plants.
6
Question 6
Genes and environment: which statement is NOT true?
- A. Environmental variation is passed on to offspring.
- B. A suntan is caused by the environment.
- C. Height depends on both genes and environment.
- D. Clones have identical genes.
7
Question 7
An organism has the genotype tt. How is this genotype described?
- A. homozygous dominant
- B. heterozygous
- C. homozygous recessive
8
Question 8
Potato pieces were left in sugar solutions. Percentage change in mass: 0 mol/dm³: +15 % 0.2 mol/dm³: +9 % 0.4 mol/dm³: +3 % 0.6 mol/dm³: −3 % 0.8 mol/dm³: −9 % Between which concentrations is the solution that matches the concentration inside the potato cells?
- A. 0–0.2 mol/dm³
- B. 0.2–0.4 mol/dm³
- C. 0.4–0.6 mol/dm³
- D. 0.6–0.8 mol/dm³
9
Question 9
Exchange surfaces: which statement is NOT true?
- A. Fish gills have many thin filaments to increase surface area.
- B. Thick walls make exchange surfaces work better.
- C. Smaller objects have a larger surface area to volume ratio.
- D. Villi increase the surface area of the small intestine.
10
Question 10
Cucumber slices sprinkled with salt become limp and watery. Why?
- A. Salt enters and the cells burst
- B. Salt particles push water out by force
- C. The cucumber starts to photosynthesise
- D. Water leaves the cells by osmosis into the more concentrated salty surface
Question 11
A structure is 10 µm wide. How wide is it in millimetres (mm)? (1 mm = 1000 µm)
Answermm
Question 12
A cube-shaped cell model has sides of 3 cm. What is its surface area to volume ratio, written as ? : 1?
Answer
Question 13
Human body cells have 23 pairs of chromosomes. How many chromosomes are in a skin cell?
Answer
14
Question 14
Why are the alveoli in the lungs so numerous and tiny?
- A. to give a huge surface area for gas exchange
- B. to make the lungs heavier
- C. to filter out food
- D. to store air for later

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Answer key: 8th grade cells, genetics and evolution

1. A. They have the same genes, so differences must be environmental
2. C. 46 (23 pairs)
3. C. phenotype
4. C. active transport of mineral ions
5. B. Active transport can move substances from a low to a high concentration.
6. A. Environmental variation is passed on to offspring.
7. C. homozygous recessive
8. C. 0.4–0.6 mol/dm³
9. B. Thick walls make exchange surfaces work better.
10. D. Water leaves the cells by osmosis into the more concentrated salty surface
11. 0.01 mm
12. 2
13. 46
14. A. to give a huge surface area for gas exchange