IGCSE unit 8 Transport in plants

Secondary use for vascular bundle in stem and why

Stability against wind, because it’s a cylinder

In a plant stem, the \*\* is on the inside and the \*\* is on the outside

xylem, phloem

functions of plant roots

Anchoring plant in soil, absorption of water & minerals, food storage

pathway of water through plant

Root hair cell, Root cortex cell, xylem vessel, mesophyll cell in leaf

Function of xylem?

Transports water and mineral ions UP the stem

Function of phloem?

Transports nutrients UP AND DOWN the stem, from source to sink

What’s the function of the lignin?

Makes the cell wall impermeable and very strong

Why are the cells of the xylem vessel dead?

No cell wall, continuous, doesn’t absorb water

Where is the cortex and what dose it contain?

It’s between the vascular bundle and epidermis, it contains starch, and sometimes chloroplasts

What uses does the epidermis have, and where is it?

It helps maintain the shape of the stem and reduce loss of water vapor, and it’s on the outside of the stem

What’s the use of the pith, and where is it?

It supports the stem, and it’s on the center

Where are the vascular bundles on the root?

In the center

How do root hair cells absorb water?

Via osmosis

How do root hair cells absorb Mineral salts?

Via active transport

What dose active transport use?

Energy from cellular respiration

Define Transpiration

Loss of water vapor through plant leaves by evaporation of the water at the surface of mesophyll cells, followed by diffusion of water vapor through stomata

Transpiration is a ___ process

Passive

What’s adhesion force?

Force between water molecule and inside of xylem vessel

What’s cohesion force?

Force that attracts water molecules to each other

Main function of Transpiration?

Creates suction force that sucks up water from roots up to leafs

What’s wilting?

Loss of plant rigidity because of turgor pressure decrease in plant’s vacuole

Why does wilting occur?

Plant doesn’t get enough water (higher transpiration rate than absorption by roots)

How does ambient humidity affect the transpiration rate?

Higher humidity, Lower transpiration rate as high water potential outside leaf

How does ambient temperature affect the transpiration rate?

High Temperature, High transpiration

How does light intensity affect the transpiration rate?

High light intensity, high transpiration rate, as the stomata open

How dose air movement affect the transpiration rate?

High air movement, high transpiration rate, as humidity around the plant decreases as wind moves it away

Define translocation

The movement of sucrose and amino acids in the phloem, from regions of production (Source), to regions of storage or regions where they are used in respiration or growth (sink)

What would be the source and sink in summer?

Source: Leaf

Sink: Bud, Roots, Fruit, Tubers

What would be the source and sink in winter?

Source: Roots, Tubers

Sink: Every cell of the plant (cellular respiration)

Define diffusion

Movement of a substance from a high concentration to a low concentration

Define osmosis

Movement of water from high to low concentration through a partially permeable membrane

Define active transport

The movement of a substance from a low concentration to a high concentration