Plant tissues: Scaling up: Biology: GCSE (9:1)

Epidermal tissue

Tissue that covers and protects the plant

Waxy cuticle

A layer on the surface of the leaf which protects the plant and reduces water loss, thicker on the upper surface

Palisade mesophyll

Photosynthetic tissue below the epidermis in a leaf, palisade cells contain high concentrations of chlorophyll and high quantities of chloroplasts for photosynthesis

Spongy mesophyll

Layer of tissue found beneath the palisade mesophyll that is packed loosely for efficient gas exchange of carbon dioxide and oxygen

Xylem

Non-living vascular tissue that carries water and dissolved minerals from the roots of a plant to its leaves, the xylem is hollow and nearby cells are lignified or dead so water can move continuously

Lignin

A chemical that provides support to xylem cells and prevents the unwanted movement of water into nearby cells

Phloem

Living and elongated vascular tissue that carries sugar and organic substances throughout a plant, the phloem has sieve plates that act as pores to allow molecules to diffuse between cells

Meristem

Undifferentiated plant tissue from which new cells are formed, found in the shoots and roots

Shoots

The aerial portion of a plant body consisting of stems, leaves and flowers

Roots

Underground plant organs that absorb water and minerals

Stomata

Small openings on the underside of a leaf through which oxygen, carbon dioxide and water can move

Guard cells

Pairs of cells that surround the stomata and control their opening and closing to optimise gas exchange and reduce water loss

Root hair cell

Cells that absorb water and mineral ions from the soil, via diffusion, osmosis or active transport using structures with a large surface area

Transpiration

The process of the movement of water through a plant and the loss of water from a plant through its leaves

Factors affecting transpiration

Changing temperature, humidity, air movement and light intensity

Rate of transpiration

The rate of water loss from a plant

Effects of factors affecting transpiration

Light, wind and heat will increase the rate of transpiration, humidity will decrease the rate of transpiration

Potometer

A device used for measuring the rate of water uptake of a plant due to photosynthesis and transpiration, a bubble of water will move along the potometer to indicate the rate of transpiration

Translocation

The transportation of sugars and amino acids around the plant via phloem tissue, sugars are prone to translocation as they are made in the leaves and needs to be transported around the plant