9.1 Plant Structure and Growth Flashcards
Define Vascular plant
Vascular Plants have conductive tissues (a vascular system) for transporting water, minerals and nutrients throughout the plant
Describe the difference in number of cotyledons between monocotyledons and dicotyledons
Monocotyledons have one cotyledon; dicotyledons have two
Describe the difference in leaf shape between monocotyledons and dicotyledons
Monocotyledons have oblong or linear shaped leaves; dicotyledons have broad leaves
Describe the difference in leaf veins between monocotyledons and dicotyledons
Monocotyledons have parallel venation; dicotyledons have net-like venation
Describe the difference in root structure between monocotyledons and dicotyledons
Monocotyledons have fibrous, adventitious roots; dicotyledons have tap roots with lateral branches
Describe the difference in number of floral organs (petals) between monocotyledons and dicotyledons
Monocotyledons have them in multiples of 3; dicotyledons have them in multiples of 4 or 5
State the location of the phloem, and the importance of this
Found in middle of leaf, allowing for optimal access for all cells
State the function of the phloem
Transports the products of photosynthesis (sugars, amino acids) to the rest of the plant
State the location of the xylem, and the importance of this
Found in middle of leaf, allowing for optimal access for all cells
State the function of the xylem
Transports water and minerals into the leaf tissue from the stem and roots
State the location of the upper epidermis, and the importance of this
On top of leaf, where light intensity and heat are greatest
State the function of the upper epidermis
Secretes waxy cuticle which conserves water
State the location of the lower upper epidermis
Bottom of leaf
State the function of the lower epidermis
Contains stomata pores which allows for gas exchange, mainly CO2
State the location of the palisade mesophyll and the importance of this
Upper half of leaf where light intensity is greatest (upper epidermal cells are transparent)
State the function of the palisade mesophyll
Main region of photosynthesis; cells absorb light
State the location of the spongy mesophyll and the importance of this
Lower half of leaf, near stomatal pores where gases and water are exchanged with the atmosphere
State the function of the spongy mesophyll
Main site of gas exchange
State the location of the vascular bundles, and the importance of this
Middle of leaf, allowing for optimal access for all cells
State the function of the vascular bundles
Spread through the leaf like a network, providing support and transporting water and the products of photosynthesis
State the location of the stomata
Bottom of leaf
State the function of the stomata
Allows movement of gasses in and out of the leaf
Define Storage organ
A storage organ is a part of a plant specifically modified to store energy. They are usually found underground (better protection from herbivores).
State the function and give an example of storage roots
Modified roots which store water or food; carrots
State the function of and give an example of stem tubers
Horizontal underground stems which store carbohydrates; potatoes
State the function of and give an example of bulbs
Modified leaf bases which allow for food storage and contain layers called scales; onion
State the function of and give an example of tentrils
Modification to leafs which allow for climbing support and attachment; cucumber
Define meristems
Regions of plant tissue where undifferentiated cells undergo rapid cell division (mitosis), and therefore growth occurs.
State the two kinds of meristems which are found in dicots
Apical meristems and lateral meristems
State the location of apical meristems
Occur at the tips of the shoots and roots
State the location of lateral meristems
Formed from the cambium cells
Outline the function of apical meristems
Responsible for primary growth
Increases height/depth of plant
Produces new leaves and flowers
Outline the function of lateral meristems
Responsible for secondary growth
Increases girth of stem for strength
Produces bark on trees
Define tropism
Bending growth of a plant towards or away from a directional stimulus
Define phototropism
Bending growth of a plant towards a source of light
Define auxin
A group of substances that promote plant growth
Explain the role of auxin in phototropism
- Auxin makes plant cells enlarge and grow
- Auxin causes cell elongation by activating pumps that expel H+ ions from the cytoplasm into the cell wall
- The resulting decrease in pH within the cell causes cellulose fibres to loosen, as the bonds which hold them together are broken
- This makes the cell wall flexible and capable of stretching when water influx promotes cell turgor
- In the shoot, auxin is eradicated by light
- The greater presence of auxin on the shaded side of the plant causes this side to lengthen, making the shoot curve towards the light
