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Biology Form 4 > Chapter 4 > Flashcards

Chapter 4 Flashcards

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1
Q

What is the polarity of water? (4)

A
  • water is an inorganic compound, consists of hydrogen & oxygen elements
  • water molecules are polar molecules because shared electron between H & O will be attracted towards O2 which is more electronegative
  • polarity produced hydrogen bonds & allows water to act as universal solvent
  • allows solutes (glucose, electrolytes) to be transported through the plasma membrane into cells for biochemical reactions
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2
Q

What is cohesive force & adhesive force of water? (3)

A
  • water molecules are attached to each other through a cohesive force
  • water molecules are also attached to other surfaces through adhesive force
  • both forces produces the capillary action which allow water to enter & move along narrow spaces (xylem tube)
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3
Q

What is the specific heat capacity of water? (3)

A
  • high specific heat capacity: 4.2 kJ/kg degree Celsius
  • 4.2 kJ of heat energy is required to raise the temperature of 1 kg of water by 1 degree Celsius
  • water absorbs a lot of heat energy with a small rise of temperature, this characteristic is very important to maintain the body temperature of organisms
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4
Q

What are organic compounds?

A
  • chemical compounds that contain carbon elements
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5
Q

What is macromolecules? (3)

A
  • large & complex molecules
  • most macromolecules are polymers comprising small molecules known as monomers (building blocks)
  • carbohydrates, proteins & nucleic acids are polymer molecules of organic compounds
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6
Q

What are the elements on carbohydrates (3), their ratio & chemical formula?

A
  • carbon , r=1
  • hydrogen, r=2
  • oxygen, r=1
  • chemical formula: (CH2O)n
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7
Q

What are the types of carbohydrates? (3)

A
  • monosaccharides (simple sugars)
  • disaccharides
  • polysaccharides (complex sugars)
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8
Q

What are monosaccharides and their characteristics? (4)

A
  • monosaccharides are carbohydrate monomers (simplest carbohydrate units)
  • can combine to form polymers through condensation
  • most taste sweet, can form crystals & dissolve in water
  • has reducing power (able to transfer hydrogen/electron to other compounds)
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9
Q

What are some examples of monosaccharides and their characteristics? (3)

A
  • glucose (found in plants [rice/wheat] & fruits [grapes], most common monosaccharide & most polysaccharides are formed from this sugar)
  • fructose ( found in honey & sweet fruits)
  • galactose ( found in milk)
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10
Q

What happens when monosaccharides are heated in Benedict’s solution? (2)

A
  • when monosaccharides is heated in Benedict’s solution, the monosaccharide will reduce the blue copper (II) sulphate to brick red precipitate of copper (I) oxide (not soluble in water)
  • all monosaccharides give this reaction (aka reducing sugars)
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11
Q

What are disaccharides? Give 3 examples.

A
  • molecules that are formed when 2 simple sugar molecules (monosaccharides) combine through condensation to form a disaccharide unit (involves removal of a water molecule)
  • sucrose (non reducing sugar)
  • maltose (reducing sugar)
  • lactose (reducing sugar)
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12
Q

How is disaccharides formed? (3 word equations)

A

glucose + glucose → maltose + water
glucose + fructose → sucrose + water
glucose + galactose → lactose + water

[→ symbolizes condensation]

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13
Q

How can disaccharides be broken down to their monosaccharide units?

A
  • through hydrolysis & addition of 1 water molecule
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14
Q

What are the word equations for break down of disaccharides to their monosaccharide units? (3)

A

maltose + water → glucose + glucose
sucrose + water → glucose + fructose
lactose + water → glucose + galactose

[→ symbolizes hydrolysis]

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15
Q

What are polysaccharides and their characteristics (5)?

A
  • sugar polymers consisting monosaccharide monomers
  • formed through condensation involving 100s of monosaccharides to form long molecular chains
  • not soluble in water du to large molecular size
  • not sweet, des not crystallize
  • can disintegrate through hydrolysis with help of dilute acid, boiling & enzyme reaction
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16
Q

State the importance of carbohydrate in cells (3)

A
  • as source of energy (glucose)
  • as food reserve (glycogen in animal cells, starch in plant cells)
  • as a support structure ( cellulose in plant cell wall)
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17
Q

What are proteins and its characteristics? (3)

A
  • a complex compound composed of carbon, hydrogen, oxygen & nitrogen ( also contain sulphur & phosphorus)
  • composed of 1/more polymers (polypeptides)
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18
Q

What are polypeptides made up of? (2)

A
  • 50 to 1000s of amino acid molecules

- amino acids are linked together through condensation

19
Q

What are dipeptides? (2)

A
  • composed of 2 amino acid molecules which are linked together by a peptide bond through condensation process (1 water molecule is removed)
  • further condensation can link more amino acids to form a polypeptide chain
20
Q

What is the word equation for amino acid to dipeptide and dipeptide broken down into amino acid? (2)

A

amino acid + amino acid → dipeptide + water [→ symbolises condensation]
dipeptide + water → amino acid + amino acid [→ symbolises hydrolysis]

21
Q

What is the importance of proteins/polypeptides in a cell? (6)

A
  • build new cells
  • repair damaged tissues
  • synthesis of enzymes, hormones, antibodies & haemoglobin
  • form building blocks (keratin in skin, collagen in bones, myosin in muscle tissues)
  • breakdown of protein/polypeptides by digestive enzymes provides energy
  • polypeptides can be disintegrated into amino acids which is used again to build the protein molecules needed by the body
22
Q

What are lipids and their characteristics? (3)

A
  • naturally occurring hydrophobic compounds found in plant & animal tissues
  • made up of C,H,O elements [ratio of hydrogen atom to oxygen atom is much higher]
  • insoluble in water but soluble in other organic solvents [ alcohol, ether, chloroform]
23
Q

State the types of lipids. (4)

A
  • fats
  • waxes
  • phospholipids
  • steroids
24
Q

State the characteristics of fats. (2)

A
  • fats & oils are triglycerides [ type of ester from the condensation of 1 glycerol molecule with 3 fatty acids molecules]
  • triglycerides can be hydrolysed again into fatty acids & glycerol through hydrolysis
25
Q

What is glycerol?

A
  • type of 3 carbon alcohol that contain 3 hydroxyl groups (-OH)
26
Q

What are the 2 types of fatty acids?

A
  • saturated fat

- unsaturated fat

27
Q

What are the similarities between saturated fats and unsaturated fats? (3)

A
  • consists of C,H,O elements
  • contains glycerol & fatty acids
  • contain nonpolar molecules
28
Q

What are the differenced between saturated fats (4) and unsaturated fays (4)?

A

Saturated fats

  • fatty acids have single bonds between carbon
  • do not form chemical bonds with additional hydrogen atom because all bonds between carbon atoms are saturated
  • solid in room temperature
  • source: butter, animal fat

Unsaturated fats

  • fatty acids have at least 1 double bond between carbon
  • double bond can receive 1/more additional hydrogen atoms because carbon atoms are unsaturated
  • liquid in room temperature
  • source: olive, fish oil
29
Q

What is the characteristic of wax? (2)

A
  • contains 1 molecule of alcohol that combine with another molecule of fatty acid
  • waterproof
30
Q

What are phospholipids and what is it made up of? (2)

A
  • major component of plasma membrane

- made up of 1 glycerol molecule combine with 2 fatty acid molecules & 1 phosphate group

31
Q

What are steroids (1) and their examples (4)?

A
  • lipids that do not contain fatty acids

- cholesterol, testosterone, estrogen, progesterone

32
Q

What are the importance of lipids in cells [Fats] (3)?

A

Fats

  • reserved energy for animals
  • liner to protect internal organs
  • heat insulator for animals
33
Q

What are the importance of lipids in cells [Wax] (2)?

A

Wax

  • important component in cuticles that cover the epidermis of leaves
  • important component in sebum secreted by skin
34
Q

What are the importance of lipids in cells [Glycolipid] (2) and [cholesterol] (1)?

A 
Glycolipids
- ensure the stability of the plasma membrane
- help in cell identification process
Cholesterol
- important in steroid hormone synthesis
35
Q

What are nucleic acids the elements that form them (5) & types (2)?

A
  • nucleic acids are 1 or 2 polymer chains comprising of nucleotide monomers
  • formed from carbon, hydrogen, oxygen, nitrogen & phosphorus
  • types: - deoxyribonucleic acid (DNA) [contains deoxyribose sugar]
    - ribonucleic acid (RNA) [contains ribose sugar]
36
Q

What are nucleotides made up of? (3)

A
  • a pentose sugar (5-carbon sugar) [ 2 types: ribose & deoxyribose]
  • nitrogenous base
  • phosphate group
    [combined together through condensation process]
37
Q

What are the 5 nitrogenous base?

A
  • adenine (A)
  • guanine(G)
  • cytosine (C)
  • thymine (T)
  • uracil (u)
38
Q

What are the characteristics of deoxyribonucleic acid (DNA)? (4)

A
  • consists 2 polynucleotide chains intertwined in opposite directions, forming the double helix
  • nitrogenous base groups on both polynucleotide chains are matched & bound together by hydrogen bonds
  • nitrogenous base for DNA: - adenine(A) with thymine (T)
    - guanine (G) with cytosine (C)
39
Q

What are the characteristics of ribonucleic acid (RNA)? ()

A
  • single polynucleotide chain shorter than DNA
  • nitrogenous bases for RNA: - adenine
    - guanine
    - cytosine
    - uracil
40
Q

What are the 3 main types of RNA involved in the protein synthesis process?

A
  • messenger RNA (mRNA)
  • ribosomal RNA (rRNA)
  • transfer RNA (tRNA)
41
Q

What is the importance of nucleic acids in a cell? (3)

A

DNA

  • carrier of hereditary information
  • determinant of characteristics in living organisms
  • contains genetic codes carried by nitrogenous bases (A,G,C,T) for polypeptide synthesis which form proteins
42
Q

Explain an example of genetic code. (4)

A
  • genetic code is written in a series of 3 bases that determine sequence of amino acids in proteins to be synthesised
    Example:
    -AUG codon on mRNA is the code for methionine acid
  • the 3-base sequence in DNA is transcribed into mRNA codons, then translated into the amino acid sequence to form a single polypeptide chain
  • means that the sequence of nucleotides in DNA determines the amino acid sequence in the polypeptide chain that builds the corresponding protein
43
Q

Explain the formation of chromosomes from DNA & proteins. (4)

A
  • chromosomes are formed from DNA polynucleotide chains that are wound around a protein called histone
  • histones don’t carry genetic information
  • DNA molecules combine with histone proteins to form nucleosomes
  • nucleosomes are intertwined to form the chromosome structure

Biology Form 4 (13 decks)

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