The material in this slide show is provided free for educational use only. All other forms of storage or reproduction are subject to copyright- please contact the National Marine Aquarium The slide show was designed and produced for the NMA by STEP, the Science Training & Education Partnership T raining & S cience E ducation P artnership

How plants grow

Plants are the Producers in nearly all Food Webs - on land and in the ocean

Light and plant growthPlants in the oceanSummaryDividing cells

Light and plant growth Plants in the ocean Summary Dividing cells

Plants grow by photosynthesis They make their own food, using light and simple materials such as water

WATER LIGHTOXYGEN HYDROGEN CARBOHYDRATE CARBON DIOXIDE HYDROGEN STEP

WATER OXYGEN CARBOHYDRATE CARBON DIOXIDE LIGHT STEP

Photosynthesis uses light energy to turn carbon dioxide and water into carbohydrate The carbohydrate can be changed into other materials to make all the components of the plant cell Oxygen is produced as a waste product

The green colour of plants is caused by chlorophyll Chlorophyll absorbs the light used in photosynthesis

Light and plant growth Plants in the ocean Summary Dividing cells

On land, there is usually plenty of sunlight Trees grow tall trunks so that they can stand above other plants that might shade them

In the ocean, most light disappears in the top 100 metres Plants cannot grow deeper than this

Plants growing attached to the seabed, like this kelp, can only grow where the ocean is shallow enough to let through enough light for growth

Too dark for growth surface 100 m 500 m 1000 m 3500 m Enough light here for growth

95% of the oceans are too deep for attached plants like kelp and seaweeds

Because rooted plants cannot grow over most of the oceans, the plants have to float close to the surface

The most important group of plants are microscopic plankton algae These are producers, just like land plants

But they look very different! This single celled plant is about one- fiftieth of a millimetre across

There may be one million of these tiny cells in each litre of surface seawater

Light and plant growth Plants in the ocean Summary Dividing cells

This can happen about once per day The tiny, single-celled plants in the ocean grow simply by dividing into two new cells

Starting with one cell, you have two after one day, and four on the second day

What will happen after a week? If the conditions are good for growth, the number of cells will double each day

DAY 1 1 cell

DAY 2 2 cells

DAY 3 4 cells

DAY 4 8 cells

DAY 5 16 cells

DAY 6 32 cells

DAY 7 64 cells

DAY million cells If they could keep dividing at this rate for a month, there would be a huge number of algal cells!

If they did, they would soon run out of the other substances which they need for growth In reality, they cannot keep growing this fast for ever

Grazing animals can remove many of the new plant cells The cells also die, sink into the deeper parts of the ocean, or are eaten

Light and plant growth Plants in the ocean Summary Dividing cells

You have seen that - All green plants on land and in the sea are producers Plants grow by photosynthesis

Most of the ocean is much too deep for plants to grow on the bottom Plants in the open ocean are mainly single-celled plankton algae You have seen that -

Plankton algae can increase fast by dividing Grazing by animals stops the number of algae from getting very large You have seen that -

NOTES for USERS The material in this slide show is designed to support the teaching of science at Key Stage 1 A full description of the slide show, and linked activities for students, can be found on the National Marine Aquarium (NMA) web-site: Teachers are free to amend the slide show in whatever way they feel fit, or to use slides in other contexts. However, please note that neither the NMA nor the designers will accept responsibility for modifications, and original material remains copyright of the NMA Individual images used in the slides are copyright of NMA or STEP, except where acknowledged separately The slides have been set up to display as A4 landscape format. If they are incorporated into other slide sequences with different display settings, change in aspect ratio and text location will occur The slide sequence contains the minimum of effects and transitions. However, there are some automated animations, and teachers will wish to make sure that they are familiar with the sequence before use in class Use the PowerPoint notes viewer to obtain additional information for some slides