3 3 Booklet (pt1) - a level aqa practice PDF

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####### Name: Teachers:Y12 AQA Biology3 Organisms exchange substances with their environment(part 1))####### (3.3) Surface area to volume ratio####### (3.3) Gas exchange####### (3.3) Digestion and absorptionLessons outline:####### 1. SA:Vol ratio / Digestion####### 2. Digestion and absorption#######...

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Teachers:

Y12 AQA Biology 3.3 Organisms exchange substances with their environment (part 1)) (3.3.1) Surface area to volume ratio (3.3.2) Gas exchange (3.3.3) Digestion and absorption

Lessons outline: 1. 2. 3. 4. 5. 6. 7.

SA:Vol ratio / Digestion Digestion and absorption Gas exchange in humans Gas exchange in humans (lung disease) Gas exchange in insects Gas exchange in fish Adaptations of the gas exchange system in plants

3.3.Organisms exchange substances with their environment

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3.3.1 Surface Area to Volume Ratio The relationship between the size of an organism or structure and its surface area to volume ratio. Changes to body shape and the development of systems in larger organisms as adaptations that facilitate exchange as this ratio reduces.

 Explain how the size of an organism affects its surface area to volume ratio, and why this is important.

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 apply your knowledge of surface area to volume ratio, to explain adaptations to body shape or the development of exchange systems

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 describe and explain the relationship between surface area to volume ratio and metabolic rate

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 calculate surface area to volume ratios when supplied with cell/organism dimensions.

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Students should be able to: Students should be able to appreciate the relationship between  surface area to volume ratio and metabolic rate.

p – prepared by reading before lesson; c – covered in class; a – notes reviewed and added to; r – revised

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3.3.3 Digestion and Absorption

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During digestion, large biological molecules are hydrolysed to smaller molecules that can be absorbed across cell membranes.

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explain the general roles of organs within the digestive system and where key events in digestion happen

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explain the purpose of digestion

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explain the role of different enzymes in the digestive process, and relate the specificity of enzymes back to protein structure

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explain the role of bile

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recall the adaptations of intestinal epithelial cells to exchange

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explain the absorption of amino acids and glucose against a concentration gradient by co-transport

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explain the role of micelles in the absorption of lipids.

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p – prepared by reading before lesson; c – covered in class; a – notes reviewed and added to; r – revised

Surface Area and Volume 1.

Name: ....................................................

/15

A scientist was studying some unusual cuboid cells. She drew and measured them. 10 mm

2.5 mm 2.5 mm

10 mm

B 2.5 mm

A 2.5 mm

2.5 mm

a)

Calculate the volumes of A and B. Put your answers in the table and show your working.

b)

Calculate the surface area of cells A and C. Put your answers in the table and show your working.

C

10 mm

2.5 mm

[2]

[2] c)

Calculate the surface area to volume ratios for the three cells. Put your answer in the form n:1 e.g. 3:1 or 2.7:1. Cell

Surface area /mm2

Volume (mm3)

[3] Surface area: volume ratio

A B C e)

37.5 62.5

The cells all receive nutrients from the blood. Which cell would receive its nutrients fastest? Cell .............................................................................................................. Reason ........................................................................................................ .....................................................................................................................

[2]

2.

Flatworms are often found gliding along the bottom of ponds – or even hanging from the surface using surface tension. They have no circulatory system and rely on diffusion oxygen across their skin. They may be up to 10 mm long. The diagram below shows a transverse section of a flatworm. a)

Draw a line on the top diagram to show what we mean by a transverse section

b)

Why are flatworms flat? ................................................................................

[1]

..................................................................................................................... c)

[1]

Similar but smaller worms called rhabdocoels have a circular transverse sections. Can you explain why they don’t need to be flat? ..................................................................................................................... .....................................................................................................................

3.

[1]

Jellyfish can grow very large. They are solid and do not have a circulatory system. The outer layer of cells is in direct contact with water - either the external seawater or seawater in the gastrovascular cavity. a)

Explain why only the outer 1mm layer of cells is metabolically active. ..................................................................................................................... .....................................................................................................................

b)

[1]

Explain why the thicker inner part of the jellyfish (the mesoglea) has very few cells – and that these cells are not very active. ..................................................................................................................... .....................................................................................................................

c)

[1]

Anemones have an gastrovascular cavity which is very folded. Explain how this helps them to be more metabolically active. ..................................................................................................................... .....................................................................................................................

[1]

Shrew-Elephant Curve1

Name …………………………………………….

1.

Draw a line of best fit on the graph

2.

The axis for the independent variable (body mass) has been drawn using a logarithmic scale (0.01, 0.1, 1, 10 etc.). Why isn’t a normal scale used?

/15

[1]

............................................................................................................................. ............................................................................................................................. 3.

[1]

Oxygen consumption is a measure of basal metabolic rate. What is meant by basal metabolic rate? ............................................................................................................................. .............................................................................................................................

4.

[1]

If you weigh 60 kg, how many litres of oxygen will you consume in a typical 50 minute lesson (O2 consumption = 0.21 dm3 kg-1 h-1). ............................................................................................................................. .............................................................................................................................

1

Schmidt-Nielsen K. (1983) Animal Physiology: Adaptation and environment . CUP

[1]

5.

Which mammal has the greatest surface area? ......................................................

[1]

6.

Which mammal has the greatest surface area to volume ratio? ...............................

[1]

7.

Mammals are warm blooded, which animal will lose heat fastest per kg body mass? .............................................................................................................................

8.

[1]

Why does this mammal need a high metabolic rate? ............................................................................................................................. .............................................................................................................................

9.

[1]

Would you expect the lungs of shrews or elephants to have the greatest surface area relative to the surface area of their body? ............................................................................................................................. Reason ................................................................................................................. .............................................................................................................................

[2]

10. Why do penguins huddle together? .............................................................................................................................

[1]

11. Why do polar bears have relatively small ears? .............................................................................................................................

[1]

12. Why do elephants have relatively large ears? .............................................................................................................................

[1]

13. Why don’t shrews have a very thick fur coat? .............................................................................................................................

[1]

14. Mammal traps used for catching small mammals have a hole so that shrews can escape. Why can’t shrews be kept overnight in the trap like mice and voles? ............................................................................................................................. .............................................................................................................................

[1]

The Intestine

1.

2.

What does each region of the digestive system do?  Stomach  Small Intestine  Large Intestine How are the following regions of the digestive system adapted?  Stomach  Small Intestine  Large Intestine

3.

Where are each of the following enzymes released and what are their substrates and products?

Amylase

Lipase

Released by which organ(s)

Substrate

Product(s)

4.

How and why are different regions of the digestive system kept at different pHs

5.

Why is pepsin released in an inactive form and then activated after release?

Protease

Name: ……………………………………………………………………………………………………..

Date: ………………………….…..

The role of active transport in absorption. 1.) Complete the key on the diagram and then match the statements below to the numbers on the diagram.

CAVITY (LUMEN) OF SMALL INTESTINE

2

3 KEY: ……………..……… Water

…………………….. ……………………..

4

INTESTINE EPITHELIAL CELL

1 BLOOD CAPILLARY

The mechanism by which amino acids are absorbed from the small intestine involves the molecule being drawn into the cells along with sodium ions that have been actively transported out by the sodium potassium pump. This is an example of co-transport.

There is now a much higher concentration of Na+ ions in the lumen of the intestine than inside the epithelial cells.

The Na+ ions diffuse into the epithelial cells down a concentration gradient through a different type of protein carrier in the cell surface membrane. As the Na+ ions flood back in through this second carrier protein they carry amino acids in with them.

Na+ ions are actively transported out of the epithelial cells by the Na+/K+ pump into the blood.

The amino acids pass into the blood plasma by facilitated diffusion using another type of carrier in the epithelial cell membrane.

Now, answer these questions: 1.) State two ways in which the movement of amino acids is maintained from the inside of the small intestine to the capillaries in the villi. ………………………………………………………………………………………………………………………………………………………………………. ………………………………………………………………………………………………………………………………………………………………………. ………………………………………………………………………………………………………………………………………………………………………. ………………………………………………………………………………………………………………………………………………………………………. ……………………………………………………………………………………………………………………………………………………………………[2] 2.) Why is the term ‘co-transport’ used to describe the transport of amino acids into cells? ……………………………………………………………………………………………………………………………………………………………………….

………………………………………………………………………………………………………………………………………………………………………. ……………………………………………………………………………………………………………………………………………………………………[1] 3.) For each of the following events in the glucose co-transport system, state the type of movement and whether the process is active or passive: a. Na+ ions move out of the epithelial cell - ……………………………………………….………….………………. b. Na+ ions move into the epithelial cell - ………………………………………………….………………….……….

c. amino acids molecules move into the epithelial cell -…………………………….………………………[3] 4.) Complete the following table:

Term Facilitated Diffusion Active Transport Carrier Molecule

Concentration gradient Na+/K+ Pump Lumen

Definition

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8 Digestion and absorption

Practising problem solving

Digestion Task introduction The digestion topic focuses mainly on digestion and absorption of carbohydrates, lipids and proteins. You should make sure you have learnt all these processes in detail, ensuring you do not mix up any of the details. You should be prepared to answer questions comparing digestion of the different components of the diet, and also apply your knowledge to questions on deficiencies/diseases which affect the digestive system. Part 1 1 a) Starch is an important component of the human diet. i) Explain why starch cannot be absorbed directly into the blood whilst glucose can.

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..................................................................................................................... ..................................................................................................................... ..................................................................................................................... .....................................................................................................................

ii) Where does the physical digestion of starch begin?

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iii) Where does the chemical digestion of starch begin? Explain your answer.

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iv) Why does the chemical digestion of starch halt in the stomach?

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© Hodder & Stoughton Limited 2015

8 Digestion and absorption

Practising problem solving

b) Starch is just one type of carbohydrate found in the human diet. i) Explain the role of the ileum in the digestion of carbohydrates.

[3]

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ii) Why are sodium ions essential for the uptake of the products of carbohydrate digestion?

[2]

..................................................................................................................... ..................................................................................................................... ..................................................................................................................... .....................................................................................................................

iii) Explain why sodium ions are actively transported out of the epithelial cells.

[2]

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v)

Cellulose is also a polymer of glucose. Explain why cellulose is not a source of glucose in human digestion.

[2]

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© Hodder & Stoughton Limited 2015

8 Digestion and absorption

Practising problem solving

Part 2 2 a)

Where does chemical digestion of proteins begin?

[1]

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