Movement of substances in and out of cells Flashcards
diffusion
net random movement of substances from an area of high to low concentration
osmosis
net random movement of water from an area of high to low water potential across a partially permeable membrane
active transport
movement of substances from an area of low to high concentration, using energy from ATP
What is the function of the transport system in plants?
leaves can receive water and
mineral ions, both for photosynthesis
What is the xylem?
tissue that transports water and mineral ions from the roots to the leaves
Describe the structure of the xylem
- made of thick walled dead cells without any cytoplasm
- cell wall with lignin
- upwards movement
- no end walls
Why doesn’t the xylem have organelles?
to prevent obstruction to flow of water and minerals
Why does the xylem have cell walls stiffened with lignin?
waterproof
strength
stops cell collapsing in
Why doesn’t the xylem have end walls?
cells join together form long tubes to make complete tissue
Give examples of mineral ions needed for photosynthesis
magnesium ions
nitrate ions
What is the use of magnesium ions in plants?
make chlorophyll for photosynthesis
What is the use of nitrate ions in plants?
make amino acids and proteins
What is the phloem?
tissue in plants that transports sugars and amino acids both up and down the plant from the leaves to respiring tissues
translocation
movement of sugars and amino acids through the phloem that uses energy
Describe the structure of the phloem
- companion cells
- sieve plates (thin layer of cytoplasm)
- cell walls of cellulose
Why does the phloem have companion cells?
keeps phloem alive
has ribosomes and cytoplasm to do this
Why does the phloem have sieve plates?
allows contents to flow through
How does translocation work?
- companion cells have mitochondria
- sucrose moved into sieve tubes by active transport
- low water potential in sieve tubes
- water moves via osmosis into sieve tubes
- high pressure created
- sucrose and water removed from phloem
Why is translocation called an active process?
energy needed
Why is the process of translocation so important?
sugars needed in growing points
- roots
- leaves