Biology · OCR Paper 1
Transport in Plants
How plants take up water and mineral ions through their roots, how water moves up the xylem by transpiration, how sugars move through the phloem by translocation, which factors change the rate of water uptake, and how a potometer measures it. Matches OCR GCSE Biology A (Gateway Science) B2.2f to B2.2j (the challenges of size). Every lesson is for both Combined Science and separate Biology, at Foundation and Higher.
Lessons
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1
Plant Tissues and Organs
A leaf is an organ made of several different tissues. This lesson names the tissues of a leaf, explains how each one is suited to its job and shows how guard…
8 terms -
2
Transpiration and the Xylem
Plants take up water through their roots and lose it from their leaves. This lesson follows the water from the soil to the stomata, and explains how root hair…
8 terms -
3
Translocation and the Phloem
Leaves make sugars, but every part of the plant needs them. This lesson explains how the phloem carries dissolved sugars to where they are used or stored, and…
8 terms -
4
Measuring Transpiration
Transpiration can be measured. This lesson explains how a potometer measures the uptake of water, how to investigate the factors that change the rate and how…
8 terms
Key terms in this chapter
All 32, gathered from every lesson.
- Epidermis
- The thin outer layer of cells that covers a leaf.
- Waxy cuticle
- A waxy layer on the upper surface of a leaf that reduces water loss.
- Palisade mesophyll
- A layer of tall, tightly packed cells full of chloroplasts, where most photosynthesis takes place.
- Spongy mesophyll
- A layer of loosely packed cells with air spaces, which allow gases to move through the leaf.
- Stoma
- A tiny pore in the lower epidermis of a leaf that allows gases and water vapour to pass. The plural is stomata.
- Guard cell
- One of a pair of cells that open and close a stoma.
- Meristem
- Tissue at the tips of shoots and roots whose cells can divide and differentiate into any type of plant cell.
- Turgid
- Firm and swollen with water.
- Root hair cell
- A cell on the surface of a root with a long thin extension that takes up water and mineral ions.
- Xylem
- Tissue made of dead hollow cells strengthened with lignin that carries water and mineral ions from the roots to the leaves.
- Lignin
- A strong material that strengthens the walls of the xylem.
- Transpiration
- The loss of water vapour from the leaves of a plant, mainly through the stomata.
- Transpiration stream
- The movement of water up the xylem from the roots to the leaves.
- Stoma
- A tiny pore in the leaf surface, controlled by two guard cells. The plural is stomata.
- Humidity
- The amount of water vapour in the air.
- Mineral ions
- Substances such as nitrate and magnesium that plants take up from the soil for healthy growth.
- Phloem
- Living tissue made of tubes of elongated cells that carries dissolved sugars around a plant.
- Translocation
- The movement of dissolved sugars through the phloem from the leaves to the rest of the plant.
- Sucrose
- The sugar in which the glucose made in photosynthesis is transported.
- Companion cell
- A cell next to a phloem cell that supplies it with energy.
- Storage organ
- A part of a plant, such as a root or tuber, where food is stored.
- Cell sap
- The solution of sugars and other substances inside the cells.
- Source
- A part of the plant where sugars are made, such as a leaf.
- Sink
- A part of the plant where sugars are used or stored.
- Potometer
- Apparatus that measures the rate at which a plant shoot takes up water.
- Capillary tube
- A very thin tube in which the bubble moves in a potometer.
- Independent variable
- The variable that is changed in an investigation.
- Dependent variable
- The variable that is measured in an investigation.
- Control variable
- A variable that is kept the same so the test is fair.
- Mean
- An average found by adding up the values and dividing by how many there are.
- Stomatal density
- The number of stomata in a given area of leaf.
- Reliable
- Giving similar results when the investigation is repeated.