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HMM/SCM1414-Biology 1

HMM/SCM1414 TUTORIAL 2 ANSWERS SECTION A 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.

A C C D C B D A C A

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HMM/SCM1414-Biology 1

SECTION B 1

(a) (i) (ii) (iii)

3 6 12

[1] [1] [1] Albumin Amino acid Peptide

(b) (i) Monomers (ii) Bonds (c)

Starch Glucose Glycosidic

[1] [1]

CH2OH CH2OH

O H

H

H

H

OH OH

+ H2 O

O

H

[1]

OH

H

CH2OH

H

OH

H

OH

CH2OH

CH2OH

H

O H

H

H

[1] + OH

OH OH

H

OH

H

OH CH2OH

H

OH

OH

Glucose (d)

H

Fructose

Hydrolysis

[1] [1]

(e) Maltose consists of two molecules of glucose; lactose consists of one molecule of glucose and galactose.

2

[1]

HMM/SCM1414-Biology 1

2

(a)

R

O

R

O

|

||

|

||

H – N – C – C – OH + H – N – C – C – OH |

|

H

H H 2O

R

O

R

O

|

||

|

||

[1]

[1]

H – N – C – C – N – C – C – OH |

|

H

H

(b) Peptide

[1]

(c)

Cytoplasm Endoplasmic reticulum/ribosome

[1] [1]

(d)

1. 2. 3. 4.

Interactions between non-polar R groups of different amino acids from hydrophobic interactions. This causes protein to fold as hydrophobic side groups are shielded from water. Where R groups contain sulfur, disulphide bonds can form between the groups. This contributes to maintenance of tertiary protein structure. Maximum

(e)

1. 2.

The repetitive coiling/folding of the polypeptide backbone of a protein due to hydrogen bond formation (between peptide linkages).

3

[1] [1] [1] [1] [3]

[1] [1]

HMM/SCM1414-Biology 1

SECTION C 1

(a)

1. 2. 3. 4. 5. 6. 7. 8.

(b)

2

Water is a (di)polar molecule. Oxygen has a partial negative charge. Hydrogen has a partial positive charge. Partial positive charge (regions) of hydrogen are attracted to chloride ions. Partial negative charge (regions) of oxygen are attracted to sodium ions. As a result, water molecules surround the (individual) sodium and chloride ions in a sphere of water molecules called hydration shell. Ions are separated (and shielded) from one another. Maximum

1. Aquatic environments have (relatively stable) temperatures. 2. Water heats up more slowly and holds its temperature longer. 3. Medium for biochemical reactions. 4. Major component of living things. Maximum 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13.

Produces more energy than carbohydrates when (metabolically) broken down. More metabolic water is produced when lipid is broken down. Metabolic water is useful to living organisms. Lipids are insoluble while carbohydrates are soluble. Thus, lipids are not easily dissolved out of cells. This contributes to the properties of phospholipid bilayer in cell membranes. Useful as insulation. Helps retain body heat. Example in subcutaneous fat beneath skin. Lipids less dense than water. This is useful for buoyancy to many aquatic animals. Lipids (as stored fat) can be used as a packing material around organ. This help prevents the organs from physical injury. Maximum

4

[1] [1] [1] [1] [1] [1] [1] [1] [7]

[1] [1] [1] [1] [3]

[1] [1] [1] [1] [1] [1] [1] [1] [1] [1] [1] [1] [1] [10]

HMM/SCM1414-Biology 1

ANSWER (TUTORIAL 3a) MCQ 1 2 3 4 5 6 7 8 9 10

B C C D A B D A C B

STRUCTURE 1a Mitochondria (L) Golgi apparatus (M) Smooth ER (N) Nucleolus (O) 1b synthesis lipid, detoxify drugs, store calcium ions, metabolize carbohydrate (any one answer) 1c receive materials through cis face in a form of vesicles, vesicles bud off through trans face. 2a desmosome, fasten cells together into strong sheets 2b Cytolasmic plaque (X) Cadherin (Y) Intermediate filaments (Z)

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HMM/SCM1414-Biology 1

ESSAY 1a

Drawing and label tylakoid and stroma (2m) Contains chlorophyll, enzymes, & other molecules involved in photosynthesis. (1m) Stroma
Fluid-filled space.
Contains DNA, ribosomes, & enzymes. (2m) Thylakoids
Interconnected sets of flat membranous sacs. (1m) Total 6 max = 5

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HMM/SCM1414-Biology 1

1b

Diagram (3m) Function of plasmodesmata: Enables cytosol to pass between cells. (1m) Water & small solutes (and sometimes proteins and RNA) pass freely between cells. (1m) Total 5

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HMM/SCM1414-Biology 1

2

Diagram (3m) Stacks of flattened membranous disks (cisternae). (1m) cis face near ER receives materials from ER. (1m) trans face buds off vesicles. (1m) dynamic structure (1m) Function Modifies products from ER. (1m) Manufactures certain macromolecules. (1m) Sorts & packages materials into transport vesicles. (1m) Produces lysosomes (1m) Total 11 max = 10

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HMM/SCM1414-Biology 1

ANSWER (TUTORIAL 3b) MCQ 11 12 13 14 15 16 17 18 19 20

D C B D B A A C D A

STRUCTURE

1a

1b 1c 2a 2b

Phospholipid (A) Peripheral protein (B) Glycolipid (C) Cholesterol (D) enhancing mechanical stability and flexibility of membrane, making it less permeable to water-soluble substances (any one answer) As antigen for cell to cell recognition As receptors – signal transduction facilitated diffusion Channel protein – hydrophilic, certain molecules or ions can use as a tunnel through membrane Carrier protein – bind to molecules and change shape to shuttle them across membrane

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HMM/SCM1414-Biology 1

ESSAY 1a

Forms a boundary that separates the interior of the cell from its external environment (1m) Gives shape, mechanical strength and protection to the cell (1m) Selectively permeable to regulate the movement of substances in and out of the cell (1m) Folding of cell membranes enables phagocytosis and pinocytosis (1m) Forms membranous organelles (1m) Total 5

1b

Transport – to transport substance across the membrane by facilitated diffusion or active transport (1m) Enzymatic activity – ex. ATP synthetase on inner membrane of mitochondrion or thylakoid membrane (1m) Signal transduction – as receptor for other substances such as hormones (1m) Cell-cell recognition – as antigen for recognition (1m) Intercellular joining – cell to cell adhesion (1m) Give structural support for plasma membrane (1m) Total 6 max = 5

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HMM/SCM1414-Biology 1

2

Diagram (3m) Size: 1 – 10 µm long. (1m) Smooth outer membranes & convoluted inner membranes infolded into cristae. (1m) Inner membrane creates two compartments, Intermembrane space and Mitochondrial matrix (1m) Have own DNA produces by internal ribosomes (1m) Semi-autonomous organelles. (1m) Dynamic organelles – moving, changing shape and dividing (1m) Some metabolic steps of cellular respiration catalyzed by enzymes in matrix. (1m) Cristae provide large surface area for enzymes that synthesize ATP. (1m) Total 11 max = 10

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