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MULTICELLULAR ORGANISMS Section 2b – Plant Meristems

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MULTICELLULAR ORGANISMS. Section 2b – Plant Meristems. Re-Cap. Can you name the following cells: Can you describe their functions. Learning Outcomes. Today we will learn: - the sites of growth in a plant - the importance of meristems - the way that cells specialise in plants. - PowerPoint PPT Presentation

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Page 1: MULTICELLULAR ORGANISMS

MULTICELLULAR ORGANISMS

Section 2b – Plant Meristems

Page 2: MULTICELLULAR ORGANISMS

Re-Cap

• Can you name the following cells:

• Can you describe their functions

Page 3: MULTICELLULAR ORGANISMS

Learning Outcomes

• Today we will learn:• - the sites of growth in a plant• - the importance of meristems• - the way that cells specialise in plants

Page 4: MULTICELLULAR ORGANISMS

How is the growth of plants different to the growth of animals?

Many plants can continue growing throughout their lifetime.

Most plant growth occurs by cell elongation, not cell division.

Many plant cells retain the ability to differentiate into any cell type. This is why cuttings can be used to create new plants.

Plant vs. animal growth

Growth in plants only occurs in certain tissues.

Page 5: MULTICELLULAR ORGANISMS

How do plants grow?

zone ofcell division

zone ofcell elongation

zone ofcell differentiation

Cell division only takes place in regions of the plant called meristems. These tissues are found in the tips of the roots and shoots – they are therefore apical meristems.

meristem

After this, cells differentiate into their final form.

Plants only get taller when cells in meristems elongate following cell division.

Page 6: MULTICELLULAR ORGANISMS

Plant Cell differentiation• Initially cells will

elongate• Then they will develop a

vacuole• - vacuolation• Then the cells will

specialise• - differentiation• Xylem• - will lose the vacuole,

and become hollow• - will develop lignin

Page 7: MULTICELLULAR ORGANISMS

Animals, plants or both?

Page 8: MULTICELLULAR ORGANISMS

Lateral Meristems

• Some plants grow every year• Their stems need to thicken to

support the extra growth• This thickening is controlled by

lateral meristems• These cause the stem to get

wider every year• This is seen in rings within the

stem

Page 10: MULTICELLULAR ORGANISMS

Re-Cap questions

• 1) What is a meristem?• 2) Identify 2 regions of a plant which possess

an apical meristem?• 3) State 2 differences between a xylem vessel

and a meristematic cell• 4) Give ONE way in which growth in an animal

differs from growth in a plant