Plant Structures and Their Functions

What Plant Structures and Their Functions covers

Plant Structures and Their Functions is examined in Paper 2, Biology 2. It covers photosynthesis and its limiting factors, investigating light intensity and the rate of photosynthesis, root hair cells, xylem and phloem, transpiration and translocation, leaf structure, the factors affecting transpiration and the potometer, plant adaptations to extreme environments, and how auxin controls phototropism and gravitropism.

The 9 subtopics

Each one has its own page.

• Photosynthesis as an endothermic reactionProducers, biomass and why animals depend on photosynthetic organisms, the word and balanced symbol equations for photosynthesis, why it is endothermic, chlorophyll in chloroplasts, where the raw materials come from, and how a plant uses the glucose and oxygen it makes.Open →
• Limiting factors in photosynthesisWhat a limiting factor is, how light intensity, temperature and carbon dioxide concentration each affect the rate of photosynthesis, why the rate levels off in bright light and falls above about 45 °C, what limits a warm, brightly lit greenhouse, and what a flat section of a rate graph shows.Open →
• Light intensity and the rate of photosynthesisMeasuring the rate of photosynthesis in pondweed, the independent and control variables in the lamp-distance investigation, using a beaker of water, sodium hydrogencarbonate, settling time and a darkened room, improving on counting bubbles, the expected results, and hypotheses, predictions, conclusions and whether data support them.Open →
• Root hair cells, xylem and phloemHow root hair cells absorb water by osmosis and mineral ions by active transport, why salty water makes a plant wilt, how dead, lignified xylem vessels carry water, and how phloem sieve tubes and companion cells use energy to move sucrose up and down the plant.Open →
• Transpiration and translocationTranspiration and the path of water from soil to air, how evaporation pulls water up the xylem, stomata and how guard cells open and close them, wilting, and the translocation of sucrose in the phloem from the leaves to growing regions and storage organs using energy from respiration.Open →
• Leaf structure for photosynthesis and gas exchangeHow the broad, thin shape and large surface area to volume ratio of a leaf suit it to photosynthesis and gas exchange, the palisade and spongy mesophyll, the waxy cuticle and transparent upper epidermis, stomata on the lower surface, and the xylem and phloem in leaf veins.Open →
• Factors affecting the rate of transpirationHow light, wind, temperature and humidity affect water uptake, setting up and using a potometer, why uptake only estimates transpiration, calculating rates per minute, per hour, by volume and per unit of leaf area, and plotting graphs, lines of best fit, gradients, intercepts and y = mx + c.Open →
• Plant adaptations to extreme environmentsHow desert, dry grassland and cold-climate plants reduce water loss with small leaves and spines, thick waxy cuticles, few stomata on the lower surface, stomata opened only at night or sunk in pits and surrounded by hairs, rolled leaves and needle-shaped leaves.Open →
• Plant hormones, phototropism and gravitropismPlant hormones and where auxin is made, phototropism and gravitropism, how auxin makes shoots bend towards light and roots grow downwards and the advantage of each response, and why a shoot with its tip removed no longer bends towards light.Open →

What you need to know

Answer each one before you reveal it.

Take Plant Structures and Their Functions further

The same content, four other ways.

Commonly confused

Pairs that lose marks when they are blurred together.

• Xylem vs Phloem

  Xylem: dead lignified vessels carrying water and mineral ions upwards. Phloem: living sieve tubes carrying dissolved sucrose up and down.

• Transpiration vs Translocation

  Transpiration: loss of water vapour from the leaves through the stomata. Translocation: movement of sucrose and other food substances through the plant.

• Phototropism vs Gravitropism

  Phototropism: growth response towards or away from the direction of light. Gravitropism: growth response to gravity, shoots away and roots towards.

Questions from this topic

Each one with the model answer underneath.

1. 1

   What is a producer in an ecosystem?

   Model answer

   A producer is an organism that makes its own food from simple substances using light energy, forming the start of a food chain.

2. 2

   What is meant by biomass?

   Model answer

   Biomass is the mass of living material present in an organism or in a group of organisms.

3. 3

   Nearly all the living material on Earth can be traced back to plants and algae. Explain why.

   Model answer

   They trap light energy and use it to build glucose, which becomes new living material that all other organisms ultimately depend on.

4. 4

   Apart from land plants, name two kinds of organism that act as producers.

   Model answer

   Algae, including the phytoplankton in oceans and lakes, and photosynthetic bacteria.

5. 5

   Explain why animals depend on photosynthetic organisms for their food.

   Model answer

   Animals cannot make their own food, so they must obtain it by eating producers or by eating other animals that ate producers.

6. 6

   Suggest what would happen to the total biomass of an ecosystem if all its producers died.

   Model answer

   Total biomass would fall at every feeding level, because no new food or stored energy would enter the ecosystem.

What is inside Levo

Six ways to work the same material.

Plant Structures and Their Functions revision questions

What does Plant Structures and Their Functions cover in Edexcel GCSE Biology?

9 subtopics: photosynthesis as an endothermic reaction, limiting factors in photosynthesis, light intensity and the rate of photosynthesis, root hair cells, xylem and phloem, transpiration and translocation, leaf structure for photosynthesis and gas exchange, factors affecting the rate of transpiration, plant adaptations to extreme environments and plant hormones, phototropism and gravitropism. Each one has its own page with questions and model answers.

How is Plant Structures and Their Functions organised?

By the Edexcel 1BI0 specification, subtopic by subtopic, so it matches the order you are taught it in.