Transporting substances in plants - Coggle Diagram
Transporting substances in plants
- dead tubes with lignin responsible for the transport of water and minerals throughout the plant. it transports water and minerals from the roots up the plant stem and into the leaves. Xylem tubes are made up of vessels (cells) that lose their end walls so it can form a continuous hollow tube. they become strengthened by a chemical called lignin. the cells are no longer alive so the lignin gives strength and supports the plant. transport through the xylem does NOT REQUIRE ENERGY
- tissue in the plant that transports the products of photosynthesis, including sugars and amino acids. it moves food substances that the plant produces to where they are needed for processes like: growing parts of the plant for use; storage organs such as bulbs; developing seeds. transport is therefore both up and down the stem and this is called translocation phloem consists of
cells that are adapted for their functions.
- specialized for transport and have no nuclei.
- transport of substances in the phloem requires energy. one of more companion cell is attached to each sieve tube to provide it with energy, a sieve tube is completely dependent on its companion cells
- the loss of water from leaves by evaporation through the stomata
- the transport of dissolved material within a plant.
adaptations of the leaf
the palisade mesophyll is adapted to absorb light efficiently. they are packed with many chloroplasts; are column-shaped and arranged closely together; are toward the upper surface of the leaf
the spongy mesophyll is used for efficient gas exchange. these cells are covered by a thin layer of water. gases dissolve in this water as they move into and out of the cells
When the plant is photosynthesizing in the light, these features allow carbon dioxide to diffuse into the spongy mesophyll cells, and oxygen to diffuse out of them.
To enter the leaf, gases diffuse through small pores called stomata. As the stomata open, water is lost by the process of transpiration. Closing the stomata helps to control water loss.
water enters the plant through the root hair cells. water gets into the root hair cells by osmosis and minerals get into the root hair cell by active transport.
factors affecting transpiration:
an increase in temp increases the molecular movement so that more water molecules evaporate from cell surfaces and the rate of diffusion of water molecules from the leaf is increased.
removes water vapour from leaf surfaces. more water vapour diffuses from the leaf.
an increase in light intensity increases the rate of photosynthesis. stomata open so that water vapour diffuses out of the leaf
factors that affect water loss
obstructing the stomata
mean no. stomata = sample 1 + sample 2 + sample 3 +sample 4 + sample 5 / no. samples
the uptake of water can be measured using a potometer. it is a piece of capillary tubing that a plant is connected to. the water unpake is measured by recording the time taken for a bubble in the tube to move a set distance
independent - time
dependent variable - distance moved by the bubble along the capillary tube
control - temp, air flow