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What is growth?
The irreversible increase in dry mass of an organism
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Why is dry mass a more reliable indicator of growth?
As the water content in an organism can vary
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Where does growth (cell division) take place in animals?
All over the body
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In plants, growth and development starts in specific regions called...?
meristems
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What is a meristem?
A group of undifferentiated plant cells capable of repeated division
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What are the two types of meristems and what type of growth are they involved in?
- Apical - primary growth
- Lateral - secondary growth
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Where is an apical meristem found?
At the tip (apex) of a root and shoot
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Put these in the correct order:
Elongation
DNA replication, mitosis and cell division
Differentiation
- 1. DNA replication, mitosis and cell division
- 2. Elongation
- 3. Differentiation
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What is secondary growth?
When the plant increases in girth
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What lateral meristem is secondary xylem made by?
Cambium
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How old is this tree?
- 3 years old
- (Do not count first or last ring!)
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In spring, what happens to the cambium activity and the shape of the annual rings?
- Cambium activity is most active in spring
- This produces large diameter, thin walled xylem vessels to allow increased flow of water and minerals for growth as buds break dormancy and new leaves grow
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In Summer, what happens to the cambium activity and the shape of the annual rings?
- Cambium is less active in summer
- Small diameter, thick walled xylem vessels produced to provide greater support and water to the additional leaves which grow on new twigs
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In winter, what happens to the cambium activity?
Cambium is inactive in winter
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Wider rings are produce by what kind of weather?
Warm and wet
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Narrower rings are produced by...?
Cold conditions, dry conditions and leaf loss
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