biology 12. arid regions usually hot and dry eg australian & african deserts & savannah can...
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Biology 12
Arid regionsUsually hot and dry eg Australian & African deserts & savannahCan be cold & dry eg icecaps & tundra
Plant adaptations - arid
Problems faced• Water availability low• Humidity low• Temperature high• Light high• Air movement high
Solutions includeIncreased roots – either deep
or wide and shallowWater storage (roots, leaves
or stems) eg cacti, boabsReduced leavesReduced stomata in leavesProtection for leaves –
cuticle, thick epidermis, curling, sunken pits, hairs to guard stomata
Closing stomata in hot conditions
Arid region adaptationsWater storageReduced leaves
Water storage -succulent leaves
Water storage - trunkReduced leaves – losesleaves in summerLong deep roots
Reduced leavesWide shallow root system
Coastal environmentsHot, dry, saline, moving sand which can cover plants
Plant adaptations - coastal
Problems faced• Water availability low• Humidity low• Temperature high• Light high• Air movement high –
lots of sand and salt
Solutions includeWide shallow root
systemsRapid growthCan cope with burialRolled leaves, sunken
stomata, reduced stomata and/or hairs
Succulent leavesSalt secretion in leaves
RainforestLow light, high humidity
Plant adaptations - wet
Problems faced• Water availability high• Humidity high• Temperature varies -
high (tropical) to medium (temperate)
• Light can vary – high in the canopy, low at ground level
• Air movement usually low
Solutions includeLarge leaves to trap
lightDeep veins to carry
water away from plantUsually many stoma
and thin epidermisLarge air spaces within
leaves
Aquatic environments
Plenty of water, problems with water logging/lack of airMarine and estuarine plants must cope with high salinity
Plant adaptations - aquatic
Problems faced• Water availability high• Humidity usually high• Temperature varies• Light usually high (may
vary if plant deeper under water)
• Air low
Solutions includeStomata on surfaces of
leaves (eg water lilies)
Large air spaces for buoyancy and gas storage
Aerial roots (eg mangroves)
Salt secretion in leaves (mangroves)
Leaf adaptations 1
Leaf adaptations 2
Leaf adaptations 3
Look at the stomata in these leaves.Which of these is most likely to be adapted to arid
conditions?This one- it has fewer stomata
Leaf adaptations 4
What adaptations can be seen in these that allow them to survive arid conditions?
Rolled leafThick cuticle and epidermis
Rolled leafSunken pitsHairs to protect stoma
Reduced stomaSunken pitsThick cuticle and epidermis
Leaf adaptations 5
What adaptations can be seen in these that allow them to survive in aquatic conditions?
Transpiration experiments
Which plants would you expect to show the greatest amount of transpiration – natives or non-natives? natives
Why? They should have adaptations for dry arid conditions to reduce water loss
Tropisms experiments
What do we expect to see in the beans? The roots should grow towards the ground/downwards = positive geotropism
What do we expect to see in the wheat tropism experiment? The uncut seedlings should bend towards the light, the cut ones will not bend
Adaptations – zoo animalsWhat adaptations can be seen in these animals?
Big ears, long thin extremities
Nocturnal, burrowing, hibernation
Nocturnal, burrowing, Very efficient kidneys
Long thin extremities
Big ears, long thin extremitiesResting/seeking shade in the heat of the dayLicking fur – evaporative cooling
Basking
Adaptations in animals - camel• Nose contains crystals that extract most of the
moisture from air leaving lungs• Stomach absorbs water• Fat in hump can be metabolised to produce
water• Fur prevents water loss from skin
Adaptations in animals - penguins
Insulating fat layer
Vasoconstriction in feet
Salt gland
Multiple choice question 11 A scientist has been studying photosynthesis in roses. After a warm
weekend the scientist notices that the leaves on the roses have wilted. The scientist picks some leaves and finds that, after observing them under a microscope, the stomata are closed. The scientist concludes that the roses are suffering from water stress. Which of the following statements BEST describes the effect of water stress on photosynthesis?
(a) There is no effect on photosynthesis itself, but the lack of water in the xylem and phloem prevents transport of the products of photosynthesis to other parts of the plant, thus inhibiting growth.
(b) The wilted leaves do not have sufficient surface area exposed to the sun to absorb light thus preventing photosynthesis.
(c) The closed stomata do not prevent gas exchange and therefore photosynthesis is not affected
(d) The closed stomata prevent gas exchange, resulting in carbon dioxide depletion and inhibition of photosynthesis.
Multiple choice question 11 A scientist has been studying photosynthesis in roses. After a warm
weekend the scientist notices that the leaves on the roses have wilted. The scientist picks some leaves and finds that, after observing them under a microscope, the stomata are closed. The scientist concludes that the roses are suffering from water stress. Which of the following statements BEST describes the effect of water stress on photosynthesis?
(a) There is no effect on photosynthesis itself, but the lack of water in the xylem and phloem prevents transport of the products of photosynthesis to other parts of the plant, thus inhibiting growth.
(b) The wilted leaves do not have sufficient surface area exposed to the sun to absorb light thus preventing photosynthesis.
(c) The closed stomata do not prevent gas exchange and therefore photosynthesis is not affected
(d) The closed stomata prevent gas exchange, resulting in carbon dioxide depletion and inhibition of photosynthesis.
Multiple choice question 22. Tortoises are terrestrial reptiles related to turtles. Some tortoises can
produce both urea and uric acid as nitrogenous waste products. Which statement about tortoises is the best explanation of this adaptation?
(a) The tortoises' diet causes them to have such large amounts of nitrogenous waste that they need to produce both compounds to excrete it all.
(b) Tortoises produce urea to repel predators but otherwise use uric acid.
(c) The tortoises excrete urea when food is plentiful and they have sufficient energy to produce it. They then switch to producing uric acid when food is scarce and they need to conserve energy.
(d) The tortoises only excrete uric acid during drier months to conserve water and switch to urea during wetter periods.
Multiple choice question 22. Tortoises are terrestrial reptiles related to turtles. Some tortoises can
produce both urea and uric acid as nitrogenous waste products. Which statement about tortoises is the best explanation of this adaptation?
(a) The tortoises' diet causes them to have such large amounts of nitrogenous waste that they need to produce both compounds to excrete it all.
(b) Tortoises produce urea to repel predators but otherwise use uric acid.
(c) The tortoises excrete urea when food is plentiful and they have sufficient energy to produce it. They then switch to producing uric acid when food is scarce and they need to conserve energy.
(d) The tortoises only excrete uric acid during drier months to conserve water and switch to urea during wetter periods.
Exam question – short answer
Giardia lamblia is a single-celled, eukaryotic organism living in the gut of endothermic hosts. This organism is unusual because it lacks several cell components present in most other eukaryotic cells.
(a) Name and describe the function of four (4) cell components present in Giardia.
(b) Name and describe the function of four (4) cell components that are missing from Giardia.
Cellular components
Present in many eukaryotic cells
Present in Giardia
Nucleus Yes Yes
Vacuole Yes Yes
Ribosomes Yes Yes
Mitochondria Yes No
Endoplasmic reticulum
Yes No
Golgi bodies Yes No
Centrioles Yes Yes
Cilia Yes No
Exam question – short answerGiardia lamblia is a single-celled, eukaryotic
organism living in the gut of endothermic hosts. This organism is unusual because it lacks several cell components present in most other eukaryotic cells.
(a) Name and describe the function of four (4) cell components present in Giardia.
Nucleus – controls cellular activity
Vacuole – stores nutrients/water
Ribosomes – protein synthesis
Centrioles – creates spindle during mitosis
Cellular components
Present in many eukaryotic cells
Present in Giardia
Nucleus Yes Yes
Vacuole Yes Yes
Ribosomes Yes Yes
Mitochondria Yes No
Endoplasmic reticulum
Yes No
Golgi bodies Yes No
Centrioles Yes Yes
Cilia Yes No
Exam question – short answerGiardia lamblia is a single-celled, eukaryotic
organism living in the gut of endothermic hosts. This organism is unusual because it lacks several cell components present in most other eukaryotic cells.
(b) Name and describe the function of four (4) cell components that are missing from Giardia.
Mitochondria – aerobic respiration
Endoplasmic reticulum – transport and modification of proteins made on ribosomes
Golgi body – packaging for secretion
Cilia - movement
Cellular components
Present in many eukaryotic cells
Present in Giardia
Nucleus Yes Yes
Vacuole Yes Yes
Ribosomes Yes Yes
Mitochondria Yes No
Endoplasmic reticulum
Yes No
Golgi bodies Yes No
Centrioles Yes Yes
Cilia Yes No
Exam question – short answer 2
Giardia lamblia is a single-celled, eukaryotic organism living in the gut of endothermic hosts. This organism is unusual because it lacks several cell components present in most other eukaryotic cells.
(c) (i) Name the type of respiration used by Giardia.
(ii) Write the word equation for this type of respiration.
(iii) What does this indicate about the natural environment of Giardia?
(d) For each of the substances listed below, state why
it is important to the functioning of Giardia and give a brief reason for your answer.
(i) ATP
(ii) Protein
Cellular components
Present in many eukaryotic cells
Present in Giardia
Nucleus Yes Yes
Vacuole Yes Yes
Ribosomes Yes Yes
Mitochondria Yes No
Endoplasmic reticulum
Yes No
Golgi bodies Yes No
Centrioles Yes Yes
Cilia Yes No
Exam question – short answerGiardia lamblia is a single-celled, eukaryotic
organism living in the gut of endothermic hosts. This organism is unusual because it lacks several cell components present in most other eukaryotic cells.
(c) (i) Name the type of respiration used by Giardia. Anaerobic/fermentation
(ii) Write the word equation for this type of respiration.
Glucose pyruvate + ATP lactic acid
(iii) What does this indicate about the
natural environment of Giardia?
Anaerobic – no oxygen present
Cellular components
Present in many eukaryotic cells
Present in Giardia
Nucleus Yes Yes
Vacuole Yes Yes
Ribosomes Yes Yes
Mitochondria Yes No
Endoplasmic reticulum
Yes No
Golgi bodies Yes No
Centrioles Yes Yes
Cilia Yes No
Exam question – short answerGiardia lamblia is a single-celled, eukaryotic
organism living in the gut of endothermic hosts. This organism is unusual because it lacks several cell components present in most other eukaryotic cells.
(d) For each of the substances listed below, state why it is important to the functioning of Giardia and give a brief reason for your answer.
(i) ATP – stores energy – captures energy from respiration and transports it around cell for other reactions to use
(ii) Protein – used to make cellular components eg cell membrane proteins, and enzymes. Enzymes catalyse reactions within cells, without which they would die.
Cellular components
Present in many eukaryotic cells
Present in Giardia
Nucleus Yes Yes
Vacuole Yes Yes
Ribosomes Yes Yes
Mitochondria Yes No
Endoplasmic reticulum
Yes No
Golgi bodies Yes No
Centrioles Yes Yes
Cilia Yes No