Growth In Plants Flashcards
What kind of tissues are the growing roots and shoots in plants?
Meristems
Describe meristems:
A region of plant tissue consisting of undifferentiated cells that are capable of continuous division
How do meristems divide?
Rapidly by mitosis
What are stem cells?
Cells that can differentiate to become any type of specialised cell
What happens to many stem cells after mitosis?
They become specialised
Where are meristems found?
Where growth takes place in a plant
Eg. Roots and shoots
Describe the function of a xylem vessel:
Responsible for transporting water and minerals from the roots to other parts of the plant
What is a xylem vessel?
Long tube formed from dead xylem cells
Where is the zone of division?
Area closest to the tip of the shoot
What happens in the zone of division?
Cells are actively dividing, producing new cells by mitosis
What happens in the zone of elongation?
Cells begin to elongate or get larger by pushing the shoot tip upwards and contributing to the lengthening of the plant
What happens at the zone of differentiation?
Start to specialise into various cell types, differentiating tissues such as xylem, phloem and other cells depending on the cells needs
What is the xylem tissue made of?
Long tube formed from many dead xylem cells
Give 4 adaptations of xylem:
- Thickened walls - carry water under pressure
- Tiny pores - allow water and minerals to enter and leave the vessel
- No cytoplasm - vessel is empty
- Lots of cell walls - to form a tube
Name 2 adaptation of a root hair cell:
- Many hairs - increase the surface area which increases rate of mineral and water absorption from the soil
- Thin walls - make the diffusion of minerals into cells more efficient
State the equation used to measure percentage growth:
Final value - Starting value
————————————- X100
Starting value
Why can measuring the change in mass of a plant over time can be used to measure the plant’s growth?
- Reflects the overall increase in cell numbers + cell size
- As plant accumulates more biomass, its mass increases, providing a quantitative measure of growth.
What is the function of guard cells?
In the day time (photosynthesis), stomata is open to enable gas exchange as the guard cells have taken water in by osmosis are are turgid (stiff/immovable)
At night (no photosynthesis), the stomata closes to prevent water loss from leaves. This is because the guard cells have lost water by osmosis and are flaccid (Flexible/shrunken)
How are guard cells adapted to their function? (3)
Bean shaped
Chloroplasts for photosynthesis
Can change shape by swelling or shrinking in response to the water pressure inside of them, thus opening and closing the stomata as necessary to maintain the plants water balance
How are palisade cells adapted to their function? (2)
Lots of chloroplasts which absorb light for photosynthesis
Brick shaped so many can fit into the top layer of the leaf
Describe the following feature of a xylem vessel that are not found in other plant cells:
Lignified walls
Thickened cells walls of the xylem which are infused with lignin to provide strength and structural support
Describe the following feature of a xylem vessel that are not found in other plant cells:
Pits
Small openings or depressions in the wall of the xylem vessel, which facilitates the lateral movement of water between vessels
Describe the following feature of a xylem vessel that are not found in other plant cells:
Hollow lumen
Hollow interior part of the xylem vessel which is a characteristic feature allowing the passage of water and minerals
Describe the following feature of a xylem vessel that are not found in other plant cells:
End wall/ Perforation plate
Found at the end of the xylem vessel with open end walls or large openings, these allow for the vertical flow of water from one vessel to the next
State 4 features of a xylem vessel that are not found in other plant cells:
- Lignified walls
- Hollow lumen
- End wall/ Perforation plate
- Pits
