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Biology - G9 Term 1 > Chapter 4: Biological Molecules > Flashcards

Chapter 4: Biological Molecules Flashcards

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1
Q

What are some forms of carbohydrates present in plants and animals? [3]

A
  1. Starch
  2. Cellulose
  3. Sugar
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2
Q

What are carbohydrates composed of? What is the ratio of these elements? [3+1]

A
  1. Carbon
  2. Hydrogen
  3. Oxygen
    One molecule of carbohydrates contains twice as many hydrogen atoms as oxygen and carbon
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3
Q

What are the simplest carbohydrates with smallest molecules? What are their properties [2]

A

Sugars. They are soluble and taste sweet.

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4
Q

What are the types of saccharides that may be formed with sugars. Give examples [3]

A
  1. Monosaccharide - sugars with a single carbon ring. Eg: glucose, fructose
  2. Disaccharide - sugars with 2 carbon rings. Eg: maltose (glucose + glucose), sucrose (glucose + fructose) and lactose (glucose + galactose)
  3. Polysaccharide - many glucose molecules joined together. Eg: glycogen (found in animals), starch (found in plants), cellulose (found in plants)
    Mono and di are soluble in water, poly isn’t.
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5
Q

What can glucose form? [3]

A
  1. Starch (found in plants)
  2. Cellulose (found in plants)
  3. Glycogen (found in animals)
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6
Q

Why is glucose turned to glycogen in animals? [2]

A
  1. It is reactive so may get involved in reactions its not supposed to be in
  2. It is soluble in water so may get carried away instead of being used by cells for energy
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7
Q

What is the monomer unit of maltose, lactose and sucrose? [3]

A

Maltose: glucose and glucose
Lactose: glucose and galactose
Sucrose: glucose and fructose

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8
Q

State the name of the test for starch [1]

A

Iodine test

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9
Q

State the name of the test for reducing sugars (eg: maltose and glucose) [1]

A

Benedict’s test

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10
Q

Describe the test to detect the presence of starch [3]

A

Crush the food sample and dissolve it in water. Add 2-3 drops of iodine solution. If starch is present, the iodine will turn from brown to blue-black. A sample with higher starch content gives a darker color. Use a colorimeter to quantify the difference in color densities.

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11
Q

Describe the test to detect the presence of reducing sugars [3]

A

Take benedicts reagent and measure 2ml. Take the food sample solution and measure the same amount, 2ml. If the sample is solid, dissolve it in water and then measure the amount. Heat in a water bath at 85 degrees Celsius. If it changes from blue to brick red, glucose is present. If it remains blue, there is no presence of glucose.

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12
Q

What are lipids (fats/oils) composed of? What is the ratio of each element to another? [3]

A
  1. Carbon
  2. Hydrogen
  3. Oxygen
    In each molecule of fat, there is much less oxygen than in a carbohydrate molecule
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13
Q

Difference between fat and oil [1]

A

A fat is a lipid that is solid at room temperature while an oil is a lipid found as liquid at room temperature

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14
Q

Are lipids soluble? [1]

A

No

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15
Q

Function of lipids [3]

A
  1. Storage of energy
  2. Make cell membranes
  3. In mammals, they act as an insulator
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16
Q

What are the monomer units of lipids? [2]

A
  1. Fatty acids
  2. Glycerol
    A fat molecule is made from 3 fatty acid molecules and 1 glycerol molecule combined together.
17
Q

What are fats soluble in? [1]

A

Ethanol

18
Q

State the name of the test to detect the presence of lipids [1]

A

Ethanol emulsion test

19
Q

Describe the test to detect the presence of lipids [3]

A

Add the food sample to 2 cm3 of ethanol, shake well. Allow to settle in a test tube rack for 2 minutes for food to dissolve in ethanol. Empty any clear liquid into a test tube containing 2 cm3 of distilled H2O. A MILKY-WHITE EMULSION is a positive result: lipid is present

20
Q

Describe the elements proteins are composed of [4]

A
  1. Carbon
  2. Hydrogen
  3. Nitrogen
  4. Oxygen
    (some contain Sulphur)
21
Q

What is the monomer unit of proteins? [1]

A

Amino Acids. Each protein is a long chain which has a precise link of amino acids.

22
Q

Importance of proteins [4]

A
  1. Enzymes are proteins
  2. Antibodies which help us fight against pathogens are proteins
  3. Hemoglobin is a protein
  4. Proteins are important in forming cell membranes
23
Q

What is the name of the test used to detect proteins? [1]

A

Biuret test

24
Q

Describe the test to detect proteins [3]

A

Place one-two spatulas of the food sample into a test tube or 1 cm3 if the sample is liquid. Add about 1 cm3 depth of water to the tube and stir to mix. Add an equal volume of potassium hydroxide solution to the tube and stir.
Add two drops of copper sulfate solution and stir for two minutes. Record the color of the solution. If protein is present the color will change to purple. The darker the color, the higher the concentration of proteins.

25
Q

State the name of the test to detect the presence of Vitamin C [4]

A

Extract juice from citrus fruit. Take equal amount of DCPIP in the same sized test tubes. Take equal volume of juice in a syringe. Count the number of drops required to turn DCPIP solution from blue to colorless. The lesser drops required, the higher Vitamin C concentration.

26
Q

Describe the structure of DNA [4]

A
  1. Two chains of nucleotides coiled together to form a double
    helix
  2. Each strand is held together by bonds that form between the bases of opposite strands
  3. Bonds between pairs of bases hold the
    strands together
  4. The bases always pair up in the same way:
    A with T, and C with G (this is called complimentary base pairing)
27
Q

What does the code in DNA do? [1]

A

Tell the cell which amino acids to link together to make proteins.

28
Q

What does the base sequences in DNA molecules determine? [1]

A

The sequence of amino acids that are used to build proteins.

29
Q

Monomer unit of DNA [1]

A

Nucleotide. Each one contains are base (A,C,T,G)

30
Q

What bond holds together amino acids to form proteins? [1]

A

Peptide bond

31
Q

What is a nucleotide? [2]

A

It is the monomer unit of DNA, made of deoxyribose sugar, phosphate and a nitrogenous base.

32
Q

Which bond holds together the bases A,T and G,C? [2]

A

Hydrogen bond. Adenine and thymine together form a double hydrogen bond, while cytosine and guanine form a triple hydrogen bond.

33
Q

What is the name of the sugar in RNA? [1]

A

Ribose

Biology - G9 Term 1 (6 decks)

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