biology quiz 3 Flashcards
Organisms respond to environmental factors called _______
stimuli
Plants have control systems called _______ which allow them to respond to changes in the environment.
Tropism
Tropism is the ______ mechanism a plant has in response to an external stimuli.
growth
plants can respond to stimuli by:
- stoma _____ and ______
- branches grow
- leaves drop off
- flowers bloom
stoma open and closes
What is phototropism?
the growth of a plant towards the light
how does phototropism help plants?
helps plant maximize the amount of light they absorb through leaves.
more photosynthesis = …
fuels further plant growth.
which part of the plant shows positive/negative phototropism (grow towards/away the light)
Leaves and stems show positive phototropism (towards) and roots show negative phototropism (away).
What is the effect of auxin?
Auxin causes cells on the shades side of the stem to grow longer than the cells on the lighted side.
What is gravitropism?
A plant’s growth response to the force of gravity.
which part of the plant shows positive/negative gravitropism (grow downwards/upwards)
Roots show positive gravitropism (grow downwards) and stems show negative gravitropism (grow upwards).
What are nastic movements?
Reaction to touch (ex. venus fly traps)
What are xylem and phloem vessels?
a system of vessels that transport water, minerals, and sugar throughout the plant.
Where are xylem and phloem vessels found?
theyre found in leaves, roots, and stems.
Xylem vessels transport what from the soil to the leaves?
water and dissolved minerals
Xylem vessels are
made up of _____ cells.
form hollow tubes consisting of only cell walls.
linked end to end, forming long continuous tubes.
dead
Water transported by xylem vessels is used for _______ and prevents wilting
photosynthesis
Phloem vessels transport ______ produced during photosynthesis.
sugars
Phloem vessels are made up of ________ joined end to end.
living cells
The cell walls in phloem vessels are ________ (contain tiny holes) allowing them to exchange materials with neighbouring cells.
porous
Sugary sap flows ____ the phloem vessels by passing through pores
down
Water and minerals enter a plant from the…
roots
At the core if the roots are the ______ and _____, surrounded by other cells.
xylem and phloem
most water uptake happens at the tip of the root by..
osmosis
Roots contain _______ which increase the surface area of roots to maximize water and mineral absorption from surrounding soil.
root hairs
minerals enter the roots by…
active transport (uses energy)
what is cohesion?
the tendency of water molecules to stick to other water molecules.
Cohesion transmits the ___________ from the tip of the leaves all the way to the roots
upwards pull
What is adhesion?
the tendency of water molecules to stick to other surfaces
Water is ______ to the wall of the xylem vessel. The clinging of xylem sap to the xylem walls helps to prevent the sap from falling back down to the roots
attracted to the wall
Water can move upward against gravity over a long distance by 2 main mechanisms: ..
pushing and pulling
The pushing force that pushes fluid upward is turgor pressure also called..
root pressure
adhesion/cohesion of the xylem sap to the xylem vessels walls helps the fluid climb upwards
adhesion
The pulling force is called..
transpiration
Transpiration
As water vapour exits the leaf by evaporation , COHESIVE forces between water molecules cause more water to be pulled UP the xylem vessels in the leaf, _________ the water that has been evaporated.
replacing
Transpiration
More water travels along the xylem vessels towards the _____ from the _____
leaf from the roots
