18 flashcards · Shared on 19 August 2026 by AtomAI Library
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What is transpiration?
The loss of water vapour from a plant's aerial parts, mainly through stomata
What is transpiration?
The loss of water vapour from a plant's aerial parts, mainly through stomata
Which substances are transported through xylem tissue?
Water and mineral ions
What is the main transport function of phloem tissue?
Transporting dissolved sugars and other organic nutrients
What does translocation mean in plants?
The movement of assimilates through the phloem from sources to sinks
Which feature makes xylem vessels well suited to carrying water?
They form continuous hollow tubes with no cytoplasm
What is the role of lignin in xylem vessel walls?
It strengthens the vessels and prevents their collapse
How does water usually enter a root hair cell from the soil?
By osmosis down a water potential gradient
Which cells regulate the opening and closing of stomata?
Guard cells
Which sequence correctly describes the main route of water through a plant?
Root hairs, xylem, mesophyll, stomata
How does water move from moist mesophyll cell surfaces to the outside air?
It evaporates into leaf air spaces and then diffuses through stomata
Why does cohesion help maintain the transpiration stream?
Water molecules stick to one another, helping form a continuous column in xylem
Which conditions would usually produce the highest transpiration rate?
Warm, dry and windy conditions
Why does increased wind speed usually increase transpiration?
It removes humid air from around the leaf
Why does high humidity usually reduce transpiration?
It reduces the water vapour concentration gradient between the leaf and the air
Which statement correctly compares xylem vessels with phloem sieve tubes?
Xylem vessels are dead at maturity, while phloem sieve tube elements are living
What does a potometer directly measure?
The rate of water uptake by a cut shoot
In phloem transport, what is a sink?
A region where assimilates are used or stored
What is a likely consequence when water loss exceeds water uptake for a prolonged period?
Cells lose turgor and the plant wilts