This a PDF I made for when I was studying Biology which consists of exam style questions from past papers which have been organised by topic and contains the key points from mark schemes which are required to gain all the marks. This is useful to learn content and also test yourself during revision...
Describe how carbon dioxide enters the leaf. (2)
• diffusion (1)
• from an area of high concentration to an area of low concentration/down a concentration
gradient (1)
• through stoma / stomata (1)
Describe the process that takes place in the leaf to produce oxygen. (3)
• (by) photosynthesis (1)
• ref to chloroplast / chlorophyll (1)
• requires carbon dioxide and water (1)
• light (energy) needed (for photosynthesis)(1)
• (to produce) glucose (1)
Explain how this change in root growth has occurred. (3)
auxin (1)
moves to / on the underside of the plant root (1)
inhibits the elongation of root cells (on the underside of the root) (1)
cells on upper side continue to elongate (1)
making the root grow downwards (towards gravity) (1)
Suggest the advantages to the plant of this response (positive gravitropism). (2)
anchor the plant /make plant stable (1)
root can reach water / absorb water / access to mineral ions (1)
The student wanted to find out where the hormone that caused the response to directional light
was found. The student had two growing plant shoots and placed them both in a window with
light coming from one direction. Describe a method the student could use to show that the
hormone was found in the tip of the plant shoot. (2)
• remove the tip from one of the plant shoots and leave the other (1)
• measure the changes in growth and direction of movement (1)
Explain how auxins cause the shoot of a plant to grow towards light. (2)
(auxins) move to the shaded side of a shoot (1)
causing cells on the shaded side to elongate (1)
Fruit ripening is one use of plant hormones.
Describe the other uses of plant hormones in crop production. (6)
• selective weedkillers
• allows broad-leaved plants to grow uncontrollably and die
• narrower-leaved plants and crops left unaffected
• auxins and or gibberellins are used
• rooting powders
• plant cuttings are dipped into rooting powder
• roots develop rapidly
• large number of plants can be produced from the same plant
• no need to wait for plants to grow from seeds
• auxins are used
• seedless fruit production
• the fruit will develop but the seeds inside will not
• fruits are able to grow larger (larger biomass)
• gibberellins are used
, Explain how active transport and diffusion provide a plant with named substances it needs for
growth. (6)
active transport requires energy
(active transport moves mineral ions) from the soil
into root (hair cells)
reference to pumps (in the cell membranes)
from a low concentration to a high concentration/against their concentration gradient
reference to mineral ions / mineral salts accept named minerals eg nitrates
diffusion is a passive process
gases diffuse from high to low concentration/down their concentration gradient
gas exchange in the leaf occurs by diffusion
carbon dioxide diffuses in
to air spaces in leaves / into cells
for photosynthesis / produces glucose
oxygen diffuses in
for respiration
Describe how stomata open (3)
• guard cells (1)
• take in water (1)
• by osmosis (1)
• (guard cells) become turgid/change shape/swell (1)
Describe how stomata close (3)
• guard cells (1)
• release water (1)
• by osmosis (1)
• (guard cells) become flaccid/change shape (1)
Use Figure 24 to help you describe how water and sucrose move through a plant. (6)
Xylem
• made of dead cells
• cells with lignin
• forming narrow/hollow tubes
• carries water / mineral ions / named mineral ion • from roots up to leaves / shoots / buds
• driven by transpiration
• where water evaporates from the leaves
• cell to cell/into/out of xylem by osmosis
Phloem
• made from living cells
• have sieve tubes
• this carries sugars / sucrose (in water)
• from the leaves
• down to roots
• up to buds / flowers
• movement by translocation
• cell to cell/into out of phloem by active transport
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