DSE Biology: Organisms and Environment — Practice Questions & Answers
How humans obtain and transport nutrients and gases, how plants transport materials and stay supported, and how energy and nutrients flow through ecosystems shaped by human activity.
888 practice questions available for this topic — here are 10 with full answers and explanations.
Which of the following is the major cause of the ascent of water in trees?
the loss of water from the leaves
the absorption of water in the roots
the thickness of the tree trunk
the diameter of the xylem vessels
Tap an answer to check it.
WhyThe loss of water from the leaves (transpiration) is the main cause of water ascent.
2Multiple choice · Medium
In a potometer experiment, the uptake of water by a leafy shoot increases when a fan is switched on because moving air
maintains a steep water-potential gradient by removing water vapour
raises the humidity around the leaf
closes the stomata
reduces evaporation
Tap an answer to check it.
WhyMoving air removes water vapour, keeping the water-potential gradient steep.
3Multiple choice · Hard
Water can rise to the top of very tall trees mainly because the cohesion between water molecules allows a continuous column to be
pulled up under tension
pushed up by root pressure alone
carried up by the phloem
lifted by capillary action only
Tap an answer to check it.
WhyCohesion lets the water column be pulled up under tension generated by transpiration.
4Fill in the blank · Medium
The tissue that conducts water and minerals upward in a plant is the .
Answer:
xylem
WhyXylem conducts water upward.
5Fill in the blank · Medium
Evaporation of water from the leaf surfaces, which generates the pull moving water up the xylem, is called .
Answer:
transpiration
WhyTranspiration generates the transpiration pull.
6Fill in the blank · Medium
Water molecules stick to one another by , allowing an unbroken water column to be drawn up the xylem.
Answer:
cohesion
WhyCohesion holds the water column together.
7Multiple choice · Easy
Chemical transmitters at synapses are involved in passing impulses (1) from a sensory neurone to an interneurone (2) from an interneurone to a motor neurone (3) from a motor neurone to a muscle. Which are correct?
(1), (2) and (3)
(1) and (2) only
(1) and (3) only
(2) and (3) only
Tap an answer to check it.
WhyChemical synapses occur at all of these junctions, including the neuromuscular junction.
8Multiple choice · Medium
Which gives the correct direction of impulse transmission within a neurone?
dendrite to cell body to axon
axon to cell body to dendrite
cell body to axon to dendrite
dendrite to axon to cell body
Tap an answer to check it.
WhyImpulses travel from the dendrites, through the cell body, to the axon.
9Multiple choice · Hard
Transmission across a synapse occurs in one direction only because the vesicles containing neurotransmitter are found only in the
presynaptic neurone
postsynaptic neurone
synaptic cleft
receptor membrane
Tap an answer to check it.
WhySynaptic vesicles are confined to the presynaptic neurone, ensuring one-way transmission.
10Fill in the blank · Medium
The small gap between two neurones is called a .
Answer:
synapse
WhyA synapse separates two neurones.
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