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IB Biology SL > B1.1 Carbohydrates and lipids > Flashcards

B1.1 Carbohydrates and lipids Flashcards

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1
Q

What is a covalent bond?

A

A covalent bond is a bond that forms when a pair of electrons are shared between two atoms.

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2
Q

How many covalent bonds can a carbon atom form?

A

A carbon atom can form four covalent bonds.

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3
Q

True or False?

Carbon is present in all four major categories of biological molecules.

A

True.

Carbon is present in carbohydrates, lipids, proteins, and nucleic acids.

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4
Q

What does the term “unsaturated” mean in relation to carbon compounds?

A

Unsaturated carbon compounds contain double or triple bonds between carbon atoms.

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5
Q

Define the term functional group.

A

A functional group is a specific group of atoms within a molecule that gives organic compounds their individual properties.

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6
Q

True or False?

Carbon dioxide contains two single covalent bonds.

A

False.

Carbon dioxide contains two double covalent bonds.

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7
Q

Why is life on Earth often described as “carbon based”?

A

Life on Earth is often described as “carbon based” because carbon is present in all major categories of biological molecules.

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8
Q

True or False?

Scientists in different countries all use the same SI units of measurement. (NOS)

A

True.

Scientists in different countries all use the same SI units of measurement to increase ease of communication and collaboration.

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9
Q

Name five SI metric unit prefixes. (NOS)

A

Five SI metric unit prefixes are: “kilo”, “centi”, “milli”, “micro” and “nano”.

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10
Q

What is a monomer?

A

A monomer is a smaller unit from which larger molecules are made.

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11
Q

Define the term polymer.

A

A polymer is a molecule made from a large number of monomers joined together in a chain.

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12
Q

What is polymerisation?

A

Polymerisation is the process by which monomers join to form polymers.

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13
Q

True or False?

All macromolecules are polymers.

A

False.

Not all macromolecules are polymers; for example, lipids are macromolecules but not polymers.

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14
Q

What is a condensation reaction?

A

A condensation reaction is a reaction where molecules combine together, forming covalent bonds and resulting in polymers or macromolecules, with water being removed as part of the reaction.

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15
Q

What is a glycosidic bond?

A

A glycosidic bond is a strong covalent bond formed between two hydroxyl (OH) groups on different monosaccharides.

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16
Q

Define the term peptide bond.

A

A peptide bond is a strong covalent bond formed between two amino acid monomers in polypeptides.

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17
Q

What is a phosphodiester bond?

A

A phosphodiester bond is a bond formed between nucleotides in nucleic acids, consisting of a phosphate group and two ester bonds.

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18
Q

What is hydrolysis?

A

Hydrolysis is a reaction where covalent bonds are broken when water is added, often used to break down macromolecules into their monomers.

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19
Q

True or False?

In hydrolysis reactions, water is produced.

A

False.

In hydrolysis reactions, water is added to break bonds, not produced.

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20
Q

What is the general formula for monosaccharides?

A

The general formula for monosaccharides is CnH2nOn, where ‘n’ is the number of carbon atoms in the molecule.

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21
Q

What is the molecular formula of glucose?

A

The molecular formula of glucose is C6H12O6.

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22
Q

True or False?

Glucose exists in two structurally different forms called isomers.

A

True.

Glucose exists in two structurally different forms: alpha (α) glucose and beta (β) glucose.

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23
Q

What are the two polysaccharides that make up starch?

A

The two polysaccharides that make up starch are amylose and amylopectin.

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24
Q

What percentage of starch is typically amylose?

A

Amylose typically makes up 10-30% of starch.

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25
Q

What is amylopectin?

A

Amylopectin is a branched polysaccharide that makes up 70-90% of starch and contains both 1,4 and 1,6 glycosidic bonds between α-glucose molecules.

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26
Q

What is glycogen?

A

Glycogen is the storage polysaccharide of animals and fungi.

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27
Q

True or False?

Glycogen is less branched than amylopectin.

A

False.

Glycogen is more branched than amylopectin.

28
Q

What is cellulose?

A

Cellulose is a structural carbohydrate found in the cell walls of plants.

29
Q

What type of glucose monomer makes up cellulose?

A

Cellulose is made up of β-glucose monomers.

30
Q

How do the hydroxyl groups differ in α-glucose and β-glucose?

A

In β-glucose, the hydroxyl group on carbon 1 sits above the carbon ring, whereas in α-glucose, it sits below the ring.

31
Q

What gives cellulose its strength?

A

Cellulose gains strength from hydrogen bonding between strands of β-glucose monomers.

32
Q

What are microfibrils?

A

Microfibrils are structures formed when several molecules of cellulose are linked by hydrogen bonds.

33
Q

Why are starch and glycogen effective storage polysaccharides?

A

Starch and glycogen are effective storage polysaccharides because they are compact and insoluble.

34
Q

What are glycoproteins?

A

Glycoproteins are structures formed by the combination of carbohydrates and polypeptides via covalent bonds.

35
Q

True or False?

Glycoproteins act as receptor molecules for cell recognition and identification.

A

True.

Glycoproteins act as receptor molecules for cell recognition and identification.

36
Q

What role do glycoproteins play in endocytosis?

A

Endocytosis is a process in which glycoproteins act as receptor molecules.

37
Q

Define antigen.

A

An antigen is a substance that can identify cells as either “self” or “non-self” and may trigger an immune response if recognised as non-self.

Glycoproteins can act as antigen.

38
Q

What determines a person’s blood type?

A

A person’s blood type is determined by the glycoprotein antigens on the surface of their red blood cells.

39
Q

What are the two main categories of lipids?

A

The two main categories of lipids are triglycerides and phospholipids.

40
Q

True or False?

Lipids are hydrophobic.

A

True.

Lipids are hydrophobic, they repel water and do not dissolve in it.

41
Q

Define triglycerides.

A

Triglycerides are lipids composed of three fatty acids bonded to a glycerol molecule.

42
Q

What is the structure of a triglyceride?

A

A triglyceride consists of a glycerol molecule and three fatty acid chains bonded by ester bonds.

These fatty acids can be either saturated (containing single carbon-carbon bonds) or unsaturated (containing double bonds).

43
Q

What is the structure of a phospholipid?

A

Phospholipids consist of a glycerol molecule, two fatty acid tails, and a phosphate head. The tails are hydrophobic, while the head is hydrophilic.

44
Q

Define ester bond.

A

An ester bond forms when the hydroxyl group of a glycerol molecule bonds with the carboxyl group of a fatty acid.

It occurs during the formation of triglycerides and phospholipids.

45
Q

What does it mean for a lipid to be amphipathic?

A

Amphipathic lipids have both hydrophobic and hydrophilic regions.

Phospholipids are an example of amphipathic molecules.

46
Q

What happens during the hydrolysis of triglycerides?

A

The hydrolysis of triglycerides releases glycerol and fatty acids, which can be used as respiratory substrates.

Three water molecules are taken in during this process as reactants.

47
Q

True or False?

Lipids are more energy-dense than carbohydrates.

A

True.

Lipids contain 2× more energy per gram than most carbohydrates due to their high number of C-H bonds.

48
Q

How are lipids stored in animals?

A

In animals, lipids are stored in adipose tissue.

Subcutaneous fats are stored below the skin. Visceral fats are stored around the major internal organs.

49
Q

What are the two forms of fatty acids?

A

Fatty acids occur in two forms: saturated and unsaturated.

50
Q

Define saturated fatty acids.

A

Saturated fatty acids have single carbon-carbon bonds in their hydrocarbon tails.

51
Q

What does it mean for a fatty acid to be “saturated” with hydrogen?

A

Each carbon atom in the hydrocarbon tail (except the final carbon) is bonded to two hydrogen atoms in saturated fatty acids.

52
Q

How do saturated fatty acids pack together?

A

Saturated fatty acids can pack tightly together due to their straight structure, increasing their melting point.

53
Q

Give an example of where saturated fatty acids are commonly found.

A

Saturated fatty acids are present in fats found in meat and butter.

54
Q

Define unsaturated fatty acids.

A

Unsaturated fatty acids have carbon-carbon double bonds in their hydrocarbon tails. They do not contain the maximum number of hydrogen atoms.

55
Q

Why do unsaturated fatty acids bend or kink?

A

The double bonds cause the hydrocarbon tail of unsaturated fatty acids to bend, making them less straight than saturated fatty acids.

56
Q

What is a monounsaturated fatty acid?

A

A monounsaturated fatty acid has one carbon-carbon double bond.

57
Q

What are polyunsaturated fatty acids?

A

Polyunsaturated fatty acids have multiple carbon-carbon double bonds.

58
Q

Why do lipids containing unsaturated fatty acids have a low melting point?

A

Unsaturated fatty acids cannot pack as tightly together as saturated fatty acids, due to their kinked structure, so fats containing unsaturated fatty acids have a low melting points are often liquids at room temperature.

59
Q

What forms the basic structure of the cell membrane?

A

Phospholipids form the basic structure of the cell membrane.

60
Q

True or False?

Cell membranes are phospholipid bilayers.

A

True.

Cell membranes consist of phospholipid bilayers.

61
Q

How does the phosphate head in a phospholipid interact with water?

A

The phosphate head is polar and soluble in water (hydrophilic), allowing it to orient towards water.

62
Q

What is a phospholipid monolayer?

A

When placed in water, phospholipids can form a single layer (monolayer) on the water’s surface.

63
Q

How does the phospholipid bilayer act as a barrier?

A

The nonpolar fatty acid tails prevent water-soluble molecules (such as sugars, amino acids, and proteins) from passing through the membrane.

64
Q

Which molecules can easily cross the lipid bilayer without transport proteins?

A

Small, nonpolar molecules like O2 and CO2 can diffuse across the lipid bilayer.

65
Q

Name two examples of steroid hormones.

A

Two examples of steroid hormones are oestradiol and testosterone.

66
Q

What allows steroid hormones to cross the lipid bilayer?

A

Steroid hormones, such as oestradiol and testosterone, contain cholesterol (a type of lipid) in their structure, allowing them to cross the lipid bilayer.

IB Biology SL (9 decks)

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