Lesson 4.5.1

4.5.1 Water and inorganic ions for plants Quiz: Pearson Edexcel Biology A (Salters-Nuffield), Unit 4

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 4.5.1, Water and inorganic ions for plants: 20 multiple choice questions for the Pearson Edexcel Biology A (Salters-Nuffield) (9BI0), Unit 4: Biodiversity and Natural Resources, written with Revision Ninja.

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The 20 questions

  1. Which ion is a component of chlorophyll?

    • Calcium
    • Magnesium
    • Potassium
    • Nitrate

  2. Which ion is used to make amino acids and nucleotides in plants?

    • Chloride
    • Calcium
    • Nitrate
    • Sodium

  3. Calcium ions are important in plants for:

    • Making chlorophyll in the chloroplast
    • Producing ATP directly in respiration
    • Forming calcium pectate in cell walls
    • Forming amino acids from nitrate

  4. Which statement describes a role of water in plants?

    • It stores energy as ATP
    • It forms peptide bonds between amino acids
    • It acts as a reactant in photosynthesis
    • It is the building material of lignin

  5. Which mineral deficiency typically causes interveinal chlorosis in older leaves?

    • Calcium
    • Sodium
    • Magnesium
    • Boron

  6. Why is turgor important to plants?

    • It makes chlorophyll from nitrate
    • It keeps cells firm and supports the plant
    • It produces ATP for photosynthesis
    • It breaks down cellulose for growth

  7. If phosphate were scarce in the soil, which molecules would a plant be least able to make in full?

    • Water and carbon dioxide
    • Cellulose and starch
    • ATP and nucleic acids
    • Lignin only

  8. A plant grown in nitrate-deficient solution shows yellowing of its older leaves first. What is the best explanation?

    • Magnesium is absent from older leaves only
    • Calcium builds up in older leaves and blocks chlorophyll
    • Nitrogen is mobile and moves to young leaves
    • Water fails to reach older leaves only

  9. Calcium deficiency often kills young growing tips. Why?

    • Calcium forms chlorophyll in young tips
    • Calcium is absorbed only through old roots
    • Calcium is mobile and is always sent to the tip
    • Calcium is immobile in the plant, so tips lack it

  10. In a solution culture experiment, plants lacking magnesium show chlorosis. Which conclusion is best supported?

    • Magnesium is needed for lignin formation
    • Magnesium is needed only for nitrate absorption
    • Magnesium is needed only for cell walls
    • Magnesium is needed for chlorophyll synthesis

  11. A student uses a complete nutrient solution as a control and one lacking nitrate as the test. What is the independent variable?

    • Plant height at the end of the experiment
    • Leaf colour at the end of the experiment
    • Time of day the plants are measured
    • Presence or absence of nitrate in the solution

  12. A core practical measures the tensile strength of plant fibres by hanging weights until they break. Which variables should be kept constant?

    • The name of the plant the fibre came from
    • Air temperature only
    • Fibre length and cross-sectional area
    • Colour of the fibre

  13. Nitrate is needed for amino acids. A deficiency would most reduce which process?

    • Protein synthesis
    • Transpiration rate directly
    • Starch hydrolysis
    • Osmosis through membranes

  14. Plant roots absorb mineral ions from soil where their concentration is low. What is the most accurate description?

    • Ions move into roots by osmosis
    • Ions move against a concentration gradient using energy from ATP
    • Ions move through the xylem only by bulk flow
    • Ions diffuse down a gradient without any energy input

  15. Which role of water is directly required for the light-dependent reactions?

    • It forms amino acids from nitrate
    • It builds cellulose microfibrils directly
    • It forms calcium pectate in the middle lamella
    • Split by photolysis, releasing electrons and oxygen

  16. Excess calcium in soil with low magnesium reduces plant growth. What is the most likely reason?

    • Calcium and magnesium compete for uptake carriers
    • Calcium makes magnesium insoluble inside the cell
    • Magnesium is only absorbed through the leaves
    • Calcium produces chlorophyll and removes magnesium

  17. A nitrogen-limited plant has less chlorophyll and less protein than a well-supplied plant. What is the best conclusion?

    • Chlorophyll contains no nitrogen
    • Nitrate travels only in the phloem and not the xylem
    • Chlorophyll and protein synthesis are limited by nitrate
    • Nitrate is needed only for cellulose production

  18. A wilted plant grows slowly. What is the best explanation?

    • The phloem stops working completely
    • Nitrate is no longer absorbed by the roots
    • Chlorophyll is destroyed by the drop in water
    • Cells cannot expand without turgor pressure

  19. Two fibres of equal cross-section are tested. Fibre A holds 3 N and fibre B breaks at 1.2 N. What is the best supported conclusion?

    • Fibre A is stronger in tension
    • Fibre B is more elastic than fibre A
    • Fibre A contains more water than fibre B
    • Fibre B is longer than fibre A

  20. Plants lacking both magnesium and nitrate are grown in the light. What is the best prediction for their photosynthesis rate?

    • Only respiration is reduced, not photosynthesis
    • Unchanged, because water is still present
    • Lower, as chlorophyll and enzymes cannot be made
    • Higher, because ATP builds up without chlorophyll

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