Chapter 02 Question

New Biology – a modern approach 1 Chapter 2: Chemicals of life ____________________________________________________________________________________

Structured Questions Core Section |!|EQA00200001|!| Complete the following paragraph with suitable words selected from the list below: changed density product

solution buoyancy respiration

stable cooling agent gametes

solvent dispersal agent

specific heat capacity reactant

Water plays an important role in life. As it is a universal (i)_________________, it helps in carrying substances to different parts of the body. Water absorbs a lot of heat with only a slight change in temperature. We say that water has a high (ii) _________________. Because of this property, oceans are relatively

(iii)

_________________ in temperature and provide a suitable habitat for aquatic organisms. Water also provides (iv) _________________ for aquatic organisms to support their body. As water takes away heat when it evaporates, it acts as a (v) _________________ to decrease the body temperature. In photosynthesis, water is a (vi) _________________ for making carbohydrates. (3 marks) ## (i)

solvent

(1/2 mark)

(ii)

specific heat capacity

(1/2 mark)

(iii)

stable

(1/2 mark)

(iv)

buoyancy

(1/2 mark)

(v)

cooling agent

(1/2 mark)

(vi)

reactant

(1/2 mark) _________ (3 marks)##

|!|EQA00200002|!| The diagram shows the food that contains a large amount of a storage substance, X.

(i)

Name the storage substance X.

(1 mark)

_______________________________________________________________________________

(ii)

X is formed from molecule Y. Name molecule Y.

(1 mark)

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New Biology – a modern approach 1 Chapter 2: Chemicals of life ____________________________________________________________________________________ _______________________________________________________________________________ (iii)

Name the three elements that form molecule Y.

(3 marks)

_______________________________________________________________________________ _______________________________________________________________________________ (iv)

Name another chemical compound (other than carbohydrate) that contains the same elements as Y. (1 mark) _______________________________________________________________________________

## (i)

Starch.

(1 mark)

(ii)

Glucose.

(1 mark)

(iii)

Carbon, hydrogen and oxygen.

(3 marks)

(iv)

Fat.

(1 mark) _________ (6 marks)##

|!|EQA00200003|!| Mary brought a lunch box to school. In the lunch box, there were bread, an orange, an egg, peanuts and a carton of milk. (i)

State the type of carbohydrate found in bread. List all the atoms which make up a carbohydrate compound.

(4 marks)

_______________________________________________________________________________ _______________________________________________________________________________

(ii)

(1) Name the organic compound found in eggs which is necessary for making cells.

(1 mark)

_______________________________________________________________________________ (2) This organic compound is too large to be absorbed. It has to be broken down into small units before absorption. Name the smallest unit.

(1 mark)

_______________________________________________________________________________ (iii)

Name TWO inorganic substances found in milk.

(2 marks)

_______________________________________________________________________________

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New Biology – a modern approach 1 Chapter 2: Chemicals of life ____________________________________________________________________________________ (iv)

Explain why peanuts have a high energy value.

(1 mark)

_______________________________________________________________________________ ## (i) (ii)

Starch is found in bread.

(1 mark)

It has carbon, hydrogen and oxygen atoms.

(3 marks)

(1) Protein

(1 mark)

(2) Amino acid

(1 mark)

(iii) Water and minerals (calcium)

(2 marks)

(iv) Peanuts contain a high content of oil.

(1 mark) _________ (9 marks)##

|!|EQA00200004|!| The photo below shows some green young seedlings:

With reference to the photo, explain the importance of water to the green young seedlings as: (i)

a reactant.

(1 mark)

_______________________________________________________________________________ _______________________________________________________________________________

(ii)

a supporting agent.

(1 mark)

_______________________________________________________________________________ _______________________________________________________________________________ ## (i)

Water acts as a reactant in photosynthesis for the production of carbohydrates in green plants. (1 mark)

(ii)

Water provides a means of support in young seedlings by contributing to turgidity of the cells. (1 mark) __________ (2 marks)##

|!|EQA00200005|!| ________________________________________________________________________________________ © Aristo Educational Press Ltd 2007 34

New Biology – a modern approach 1 Chapter 2: Chemicals of life ____________________________________________________________________________________ Read the passage below and answer the questions that follow: CHEMICAL COMOUNDS Chemical compounds are conventionally divided into two groups: organic and inorganic. Both are found in living things. Until the German chemist Friedrich Wöhler synthesized urea in 1828, it was thought that organic compounds could only be formed in living things. In fact organic matter was thought to be unique to living systems. Since Wöhler’s experiment, hundreds of organic compounds have been synthesized and it is clear that they are absolutely not unique to living things.

(i)

(1) Give FOUR principal organic compounds found in living things.

(4 marks)

_______________________________________________________________________________ _______________________________________________________________________________ (2) Besides carbon, what elements are also found in all organic compounds?

(2 marks)

_______________________________________________________________________________ (3) Select, from your answers in (1), TWO of the organic compounds which can be stored in living things.

(2 marks)

_______________________________________________________________________________ (ii)

Name ONE inorganic compound that makes up about 70 % of a living thing.

(1 mark)

_______________________________________________________________________________ ## (i)

(ii)

(1) Carbohydrates, fats, proteins and nucleic acids.

(4 marks)

(2) Hydrogen and oxygen.

(2 marks)

(3) Carbohydrates and fats.

(2 marks)

Water.

(1 mark) _________ (9 marks)##

|!|EQA00200006|!| Refer to the figure below:

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New Biology – a modern approach 1 Chapter 2: Chemicals of life ____________________________________________________________________________________

State the role of water in the above organ.

(2 marks)

________________________________________________________________________________________ ________________________________________________________________________________________ ________________________________________________________________________________________ ## The organ above is an eyeball. The aqueous humour and vitreous humour in the eyeball contain a lot of water.

(1 mark)

This gives the shape of the eye in vertebrates (as a supporting agent).

(1 mark) _________ (2 marks)##

|!|EQB00200007|!| *

Mary got three food samples: A.

C.

butter

potatoes

B.

fish

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New Biology – a modern approach 1 Chapter 2: Chemicals of life ____________________________________________________________________________________ (i)

Each food sample is a rich source of an organic compound. Complete the table below: Food sample A

Rich in

(6 marks)

Function of the organic compound in human

B C (ii)

(1) State the common elements found in the above organic compounds.

(2 marks)

_______________________________________________________________________________ (2) State ONE element that must be present and is unique to the organic compound in B. (1 mark) _______________________________________________________________________________ ## (i) Food sample A B C

Rich in fat protein starch

Function of the organic compound in human As an energy store. As a structural component of cell membrane. Glucose formed from digestion of starch is an energy source. (1 mark each) (6 marks)

(ii) (1) Carbon, hydrogen and oxygen.

(2 or 0 marks)

(2) Nitrogen.

(1 mark) _________ (9 marks)##

|!|EQB00200008|!| *

Miss Chan gave John the chemical formulae of four compounds: C6H12O6 A (i)

CH3(CH2)16COOH B

C

NH2CH2COOH

H2CO3

D

Using the letters given, state the compound which is: (1) an amino acid. Suggest a reason to support your answer.

(2 marks)

_______________________________________________________________________________ (2) inorganic.

(1 mark)

_______________________________________________________________________________

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New Biology – a modern approach 1 Chapter 2: Chemicals of life ____________________________________________________________________________________ (ii)

Calculate the ratio of hydrogen to oxygen atoms in: (1) compound A

(1 mark)

_______________________________________________________________________________ (2) compound B

(1 mark)

_______________________________________________________________________________

(iii) According to the calculated ratios, identify: (1) compound A

(1 mark)

_______________________________________________________________________________ (2) compound B

(1 mark)

_______________________________________________________________________________ (iv) Describe TWO uses of compound A in the body of a plant.

(2 marks)

_______________________________________________________________________________ _______________________________________________________________________________ ## (i)

(1) C because it contains nitrogen. (2) D

(ii)

(2 marks) (1 mark)

(1) H:O = 2:1

(1 mark)

(2) H:O = 18:1

(1 mark)

(iii) (1) Carbohydrate or glucose. (2) Fat.

(1 mark) (1 mark)

(iv) Used in respiration to release energy. Converted to starch for energy storage. Converted to cellulose for building cell wall in plant cells. (any two)

(2 marks) _________ (9 marks)##

|!|EQA00200009|!| Carbohydrates are the main components in our diet. However, the proportion of carbohydrates in the human body is far smaller than that of fats and proteins. Why?

(5 marks)

____________________________________________________________________________________ ____________________________________________________________________________________ ____________________________________________________________________________________ ____________________________________________________________________________________ ____________________________________________________________________________________ ## Carbohydrates are mainly used to release energy for daily needs in humans,

(1 mark)

hence only a small amount of carbohydrates is stored in the body.

(1 mark)

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New Biology – a modern approach 1 Chapter 2: Chemicals of life ____________________________________________________________________________________ Fats are stored in the body for energy reserve

(1 mark)

and proteins are used for body building.

(1 mark)

Thus, large amounts of fats and proteins are found in the body.

(1 mark) _________ (5 marks)##

|!|EQA00200010|!| The diagram below shows part of the cellulose molecule: …－#－#－#－#－#－… Key: #: molecule A

(i)

Name molecule A.

(1 mark)

_______________________________________________________________________________

(ii)

State a major use of molecule A in the human body.

(1 mark)

_______________________________________________________________________________

(iii) Excess molecule A can be stored in animals and plants. Name its storage forms in animals and plants respectively.

(2 marks)

_______________________________________________________________________________

(iv) Suggest ONE food source of molecule A.

(1 mark)

_______________________________________________________________________________ ##

(i) glucose (1 mark) (ii) to release energy (iii) in animals: glycogen in plants: starch

(iv) candy / chocolate (or any reasonable answers)

(1 mark) (1 mark) (1 mark) (1 mark) __________ (5 marks)##

|!|EQA00200011|!| Refer to diagrams A and B below:

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New Biology – a modern approach 1 Chapter 2: Chemicals of life ____________________________________________________________________________________

(i)

A B Classify A and B in the above diagrams as fat or oil. Explain your answers.

(2 marks)

_______________________________________________________________________________ _______________________________________________________________________________

(ii)

What is the difference of the hydrogen-to-oxygen ratio between fats and carbohydrates? (2 marks) _______________________________________________________________________________ _______________________________________________________________________________

(iii) State TWO functions of fats.

(2 marks)

_______________________________________________________________________________ _______________________________________________________________________________ _______________________________________________________________________________ ##

(i) (ii)

A is fat as it is in solid state at room temperature.

(1 mark)

B is oil as it is in liquid state at room temperature.

(1 mark)

The hydrogen and oxygen atoms in a carbohydrate molecule are in the ratio of 2:1, while a fat molecule has such a ratio higher than 2:1.

(2 marks)

(iii) - to act as an energy store - to prevent heat loss - to act as a cushion to protect internal organs - as a component of the cell membrane

(any two or any reasonable answers)

(2 marks) __________ (6 marks)##

|!|EQA00200012|!| Which of the following are examples of proteins or carbohydrates? antibody, glucose, enzyme, starch, glycogen, cellulose Put their names under the corresponding headings.

(6 marks)

Proteins Carbohydrates ________________________________________________________________________________________ © Aristo Educational Press Ltd 2007 40

New Biology – a modern approach 1 Chapter 2: Chemicals of life ____________________________________________________________________________________

## Proteins: antibody, enzyme.

(1 mark each)

Carbohydrates: glucose, starch, glycogen, cellulose.

(1 mark each)

(2 marks) (4 marks) _________ (6 marks)##

|!|EQA00200013|!| State the roles of water in sweat, blood plasma and urine respectively.

(4 marks)

____________________________________________________________________________________ ____________________________________________________________________________________ ____________________________________________________________________________________ ____________________________________________________________________________________ ____________________________________________________________________________________ ____________________________________________________________________________________ ## Sweat: water carries away heat when it evaporates.

(2 marks)

Blood plasma: water carries many dissolved nutrients and wastes around the body.

(1 mark)

Urine: water carries wastes out of the body.

(1 mark) _________ (4 marks)##

|!|EQA00200014|!| The figure below shows a tooth of an animal:

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New Biology – a modern approach 1 Chapter 2: Chemicals of life ____________________________________________________________________________________

(i)

State the major minerals that can be found in the outer white layer of the tooth.

(2 marks)

_______________________________________________________________________________ (ii)

Where else can we find the same minerals in the animal?

(1 mark)

_______________________________________________________________________________ (iii)

How can animals obtain enough minerals to maintain good health? Suggest ONE food example that is rich in the minerals mentioned in (i).

(2 marks)

_______________________________________________________________________________ _______________________________________________________________________________ ## (i)

Calcium

(1 mark)

Phosphate (or Calcium phosphate).

(1 mark)

(ii)

Bones

(1 mark)

(iii)

Animals can obtain enough minerals from their diet.

(1 mark)

Milk / cheese / fish (any one or any reasonable answers)

(1 mark) _________ (5 marks)##

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New Biology – a modern approach 1 Chapter 2: Chemicals of life ____________________________________________________________________________________ |!|EQB00200015|!| *

Water serves many important functions in plants. Suggest the roles water plays in the plants shown below so that they can survive in such a habitat.

(4 marks)

____________________________________________________________________________________ ____________________________________________________________________________________ ____________________________________________________________________________________ ____________________________________________________________________________________ ____________________________________________________________________________________ ____________________________________________________________________________________ ____________________________________________________________________________________ ##

-

Water is a universal solvent that allows many inorganic substances to dissolve in it. Carbon dioxide and oxygen must first dissolve in the water film on the mesophyll layer and later be absorbed into the plant.

-

Water can be used to transport the sugars produced and the mineral salts absorbed in the vascular bundles to other parts of the plant.

-

Under sunlight, water is split and acts as a raw material for photosynthesis. Water evaporates from the plant surface by transpiration. At the same time, water carries heat away and helps to cool down the plants to prevent overheating.

-

The pond of water provides buoyancy to the floating plants, increasing the amount of sunlight that the plants can reserve for photosynthesis. (any four or any reasonable answers) __________ (4 marks)##

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New Biology – a modern approach 1 Chapter 2: Chemicals of life ____________________________________________________________________________________ |!|EQB00200016|!| *

Classify the following items into TWO major categories (organic or inorganic). State ONE function for each substance in the human body. Present the answers in table form.

(7 marks)

Iron, fats, glycogen, nucleic acids

## Category (½ mark each)

Substance(s) (½ mark each)

Function(s) in human body (1 mark each)

(1 mark)

(2 marks)

(4 marks)

Organic

Inorganic

Fats

Prevent heat loss

Glycogen

Acts as energy reserve in humans

Nucleic acids

Carry genetic information

Iron

Forms part of the haemoglobin _________ (7 marks)##

|!|EQA00200017|!| In a laboratory, a bottle of liquid carbohydrate is put alongside a bottle of unknown pure organic substance. The labels of both bottles are missing. However, a note was found on each bottle, only stating the chemical formula:

(i)

A Chemical formula C12H22O11 Calculate the hydrogen to oxygen ratios for A and B.

B C16H32O2 (2 marks)

_______________________________________________________________________________ _______________________________________________________________________________ (ii)

Suggest which bottle, A or B, is carbohydrate. Explain your answer.

(2 marks)

_______________________________________________________________________________

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New Biology – a modern approach 1 Chapter 2: Chemicals of life ____________________________________________________________________________________ (iii)

Suggest TWO possible forms of carbohydrate that can be found in plants.

(2 marks)

_______________________________________________________________________________

(iv) It is known that two states of B, solid and liquid, are possible at room temperature. Suggest the names of the two states of B.

(2 marks)

_______________________________________________________________________________ (v)

State TWO similarities between organic substances A and B.

(2 marks)

_______________________________________________________________________________ ## (i) (ii) (iii) (iv) (v)

A: H=22, O=11; (22/11)=2

(1 mark)

B: H=32, O=2; (32/2)=16

(1 mark)

A

(1 mark)

A has a hydrogen to oxygen ratio of 2:1.

(1 mark)

starch

(1 mark)

cellulose (or any reasonable answers)

(1 mark)

Solid: fats

(1 mark)

Liquid: oils

(1 mark)

- Both can be oxidized to release energy. - Both contain carbon, hydrogen and oxygen atoms. - Both can be used for energy storage. (any two or any reasonable answers)

(2 marks)

_________ (10 marks)##

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