Bio y9 2nd half - plants Flashcards
in Guard cells the stoma is open when…
there is light and an excess of water
this means the Guard cells are swollen / turgid
in Guard cells the stoma is closed when…
it’s dark and when there’s a drought
this means the Guard cells are shrunken / flaccid
cuticle
protects the leaf
upper epidermis
Epidermal tissues cover the leaf letting light penetrate through
palisade cell
contains lots of chloroplast’s to absorb lots of light energy carrying out photosynthesis
Spongy mesophyll
irregularly shaped to have many air spaces between the cells for gases to diffuse easily and to reach all cells
Lower epidermis
Has many stomata which allow gases and water vapour to diffuse
Protect the underside of the leaf
Guard Cells
Surround this stoma on the underside of the leaf open and close the stoma to allow CO2 to get to the cells and oxygen to leave via diffusion. Also allows for some water movement.
Root hair cells
narrow tubes with large surface areas to increase the rate of mineral ions absorption.
contain lots of mitochondria , which release energy from glucose during respiration in order to provide the energy needed for active transport.
Xylem
Thexylemtransports water and minerals from the roots up the plant stem and into the leaves.
most of the cells that make up the xylem are specialized cells called vessels.
Vessels
Lose their end walls so the xylem forms a continuous, hollow tube.
Become strengthened by a chemical calledlignin. The cells are no longer alive. Lignin gives strength and support to the plant. We call lignified cells wood.
Transport in the xylem is a physical process. It does not require energy.
Phloem
Thephloemmoves food substances that the plant has produced by photosynthesis to where they are needed for processes such as:
growing parts of the plant for immediate use
storage organs such as bulbs andtubers
developing seeds.
Transport in the phloem is therefore both up and down the stem.
Translocation
teansport of substances in the phloem
Sieve tubes
specialised for transport and have nonuclei. Each sieve tube has a perforated end so itscytoplasmconnects one cell to the next.
Transpiration
the evaporation slash loss of water from the leaves through the stoma, which causes water to be drawn up the plant