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