Exchange and Transport Exam Questions Flashcards
Ventilation of the lungs involves muscles working together.
Which option describes expiration?
A In expiration at rest, the external intercostal muscles and the diaphragm relax and the rib
cage moves down and in.
B In expiration at rest, the internal intercostal muscles and the diaphragm contract pulling the
rib cage down and in.
C In forced expiration, the diaphragm relaxes and the external intercostal muscles contract
pulling the rib cage down and in.
D In forced expiration, the internal intercostal muscles and the diaphragm contract pulling the
rib cage down and in.
A
State two functions of xylem cells. (2 marks)
- Transport of water
- Structural support
Explain how two features, show that this tissue is adapted to its function (vascular tissue). (4 marks)
- Lignin provides support and prevents water loss.
- Spiral thickening allows flexibility.
- Hollow vessels minimise resistance to the flow of water.
- Bordered pits allows movement of water between xylem.
Water is transported across the root of a plant by more than one pathway.
Which of the following statements about water molecules moving via the symplast pathway is not
correct?
A Water molecules can move from cell to cell without crossing a membrane.
B Water molecules can pass through the Casparian strip.
C Water molecules must pass through the endodermis.
D Water molecules travel between cells down a water potential gradient.
B
Explain how glucose produced in photosynthesis is translocated to parts of the plant where
glucose is metabolised or stored. (6 marks)
Phloem loading:
- Glucose is converted to an assimilate/sucrose in
photosynthesising cells
- Apoplast route is an active process, proton pump in companion cells maintains the H+ concentration gradient
- Involves the co-transport of H+ and sucrose into companion cell
- Structural adaptations of companion cells, e.g. many
mitochondria, increase surface area of cell surface
membranes
- Passive loading via symplast route
- The plasmodesmata allows substances to directly travel from the cytoplasm of one cell to anothers
- entry of sucrose/solutes decreases water potential of phloem/sieve elements
- water enters phloem from surrounding cells/xylem
- results in higher hydrostatic pressure
Mass flow:
- Bulk transport of sucrose caused by pressure difference
- Entry/exit of water/solutes affects hydrostatic
pressure
- Movement from source to sink (leaf is source and root is sink)
- hydrostatic pressure gradient allows assimilates to travel from source to sink
- High hydrostatic pressure in source phloem explains
rapid transport over long distance
Phloem unloading:
- Diffusion of sucrose from phloem to surrounding cells
- Sucrose converted back to glucose
- Glucose used for respiration and converted to starch for storage
- Concentration gradient of sucrose maintained between phloem and cells
- Unloading occurs wherever cells need glucose/sucrose
- Loss of sucrose/solutes increases water potential of the phloem
- water leaves phloem to surrounding cells/xylem
- results in lower hydrostatic pressure
State the effect on the water potential of the blood if the concentration of glucose increases. (1 mark)
- Water potential decreases
Explain why the oncotic pressure of the blood depends only on the concentration of
large plasma proteins. (2 marks)
- large plasma proteins cannot pass out through the capillary wall/leave the blood, but other solutes can
- an imbalance of large plasma proteins between blood and
tissue fluid results in oncotic pressure
Indicate whether the following statements are true or false:
1. Lymph is similar in composition to tissue fluid but has more
oxygen.
2. Tissue fluid does not contain lymphocytes because they are too
large to pass through the capillary wall.
3. Lymph contains more protein than tissue fluid because of
antibody production by plasma cells.
- False
- False
- True
Which of the following statements, A to D, does not correctly describe the structure or formation
of plant vascular tissues?
A Companion cells are linked to xylem vessels by plasmodesmata.
B Mature sieve tube elements do not contain nuclei.
C Phloem and xylem are formed by differentiation of vascular meristems.
D Xylem vessels have non-lignified pits to allow movement in and out.
A
Large multicellular animals need a transport system for oxygen and carbon dioxide.
Large multicellular plants do not need a transport system for oxygen and carbon dioxide.
Which of the following statements, A to D, correctly explains these observations?
A Large plants have a low surface area to volume ratio.
B Plant cells have a low metabolic rate.
C Plants generate ATP during photosynthesis, so they do not need to respire.
D Plants generate oxygen during photosynthesis.
B
Which of the following statements, A to D, describes the movement of water across plant roots?
A The Casparian strip blocks movement by the symplast pathway.
B The symplast pathway requires water to cross partially permeable membranes.
C Water moves from the soil to the root hair cells up a water potential gradient.
D Water moves through the leaves only by the symplast pathway and across the roots only by
the apoplast pathway
B
Which of the following statements about water transport in plants is/are correct?
1 Transpiration happens as a consequence of the need for gas exchange.
2 There are cohesive forces between water molecules because they form hydrogen bonds with
one another.
3 Water is drawn up the stem due to adhesive forces between water molecules.
A 1, 2 and 3
B only 1 and 2
C only 2 and 3
D only 1
B
Ventilation of the lungs creates air movements that can be measured and recorded.
(i) Name the apparatus used to measure and record these air movements. (1 mark)
Spirometer
What structural features (cartilage, elastic fibres and goblet cells) do the trachea, bronchi, bronchioles, alveoli contain?
- Trachea: cartilage, elastic fibres and goblet cells.
- Bronchi: cartilage, elastic fibres and goblet cells.
- Bronchioles: cartilage and elastic fibres.
- Alveoli: elastic fibres.
Complete the following statements about exchange surfaces.
Use the correct terms selected from the list below:
circulatory system concentration gradient diffusion pathway
flow of air lung capacity surface area
surface area to volume ratio ventilation
Large organisms have a large ……………….. but they
have a small ……………….. . This means they need
a specialised exchange surface and a ………………. .
Two features of an efficient exchange surface are:
1. A good blood supply to maintain the ……………….. .
2. A short …………………….
- surface area
- surface area to volume ratio
- circulatory system
- concentration gradient
- diffusion pathway
