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A level Biology - Module 2 > 3.1 Biological elements (2.1.2) > Flashcards

3.1 Biological elements (2.1.2) Flashcards

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1
Q

Cells are the building blocks of all living organisms. What smaller components are they made up of?

A

Molecules

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2
Q

What are different types of atoms called?

A

Elements

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3
Q

How are different elements distinguished?

A

By the number of protons in their atomic nuclei.

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4
Q

All living things are made primarily from four key elements. What are these?

A

Carbon (C), Hydrogen (H), Oxygen (O), and Nitrogen (N).

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5
Q

What are 2 elements that also have important roles in the biochemistry of cells?

A

Phosphorus (P) and Sulfur (S)

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6
Q

Describe how a covalent bond occurs

A

A covalent bond occurs when two non-metal atoms share a pair of electrons. The electrons used to form bonds are unpaired and present in the outer orbitals of the atoms.

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7
Q

What is an atom or molecule in which the total number of electrons is not equal to the total number of protons called?

A

An ion

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8
Q

What is an atom/molecule called when it loses electrons?

A

Cation

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9
Q

What is an atom/molecule called when it gains electrons?

A

Anion

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10
Q

What happens in ionic bonds?

A

In ionic bonds, one atom in the pair donates an electron and the other receives it. This forms positive and negative ions that are held together by the attraction of the opposite charges.

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11
Q

What are ions in solutions called?

A

Electrolytes

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12
Q

What are calcium ions necessary for? (2)

A
  • Nerve impulse transmission
  • Muscle contraction
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13
Q

What are sodium ions necessary for? (2)

A
  • Nerve impulse transmission
  • Kidney function
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14
Q

What are potassium ions necessary for? (2)

A
  • Nerve impulse transmission
  • Stomatal opening
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15
Q

What are hydrogen ions necessary for? (2)

A
  • Catalysis of reactions
  • pH determination
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16
Q

Name 5 cations with useful roles

A
  • Calcium ions
  • Sodium ions
  • Potassium ions
  • Hydrogen ions
  • Ammonium ions
17
Q

Name 5 anions with useful roles

A
  • Nitrate ions
  • Hydrogen carbonate ions
  • Chloride ions
  • Phosphate ions
  • Hydroxide ions
18
Q

What are nitrate ions necessary for?

A

Nitrogen supply to plants for amino acid and protein formation

19
Q

What are hydrogen carbonate ions necessary for?

A

Maintenance of blood pH

20
Q

What are chloride ions necessary for?

A

Balance positive charge of sodium and potassium ions in cells

21
Q

What are phosphate ions necessary for? (3)

A
  • Cell membrane formation
  • Nucleic acid and ATP formation
  • Bone formation
22
Q

What are hydroxide ions necessary for? (2)

A
  • Catalysis of reactions
  • pH determination
23
Q

What 3 elements are present in carbohydrates?

A

Carbon, Hydrogen and Oxygen

24
Q

What 3 elements are present in lipids?

A

Carbon, Hydrogen and Oxygen

25
Q

What 5 elements are present in proteins?

A

Carbon, Hydrogen, Oxygen, Nitrogen and Sulfur

26
Q

What 5 elements are present in nucleic acids?

A

Carbon, Hydrogen, Oxygen, Nitrogen and Phosphorus

27
Q

What is a condensation reaction?

A

A reaction occurs when two molecules are joined together with the removal of water.

28
Q

What is a hydrogen bond?

A

A weak interaction that can occur wherever molecules contain a slightly negatively charged atom bonded to a slightly positively charged hydrogen atom.

29
Q

What is a hydrolysis reaction?

A

A reaction in which two molecules are split apart with the addition of water

30
Q

What are condensation and hydrolysis reactions responsible for in living things?

A

Condensation and hydrolysis reactions are responsible for linking and splitting apart biological molecules in living things.

31
Q

What are two monomers that are joined together called?

A

A dimer

32
Q

In condensation reactions, what happens to the -OH groups of each molecule?

A

H20 is added in hydrolysis and H20 is removed in condensation.

33
Q

Which biological molecule doesn’t form polymers like the rest?

A

Lipids

34
Q

Describe what atoms water consists of and how they are bonded

A

Water consists of two hydrogen atoms, each covalently bonded to the oxygen atom.

35
Q

Describe why water molecules are polar

A

The oxygen atom has a greater number of positive protons in its nucleus; this exerts a stronger attraction for the shared electrons. This means the oxygen atom becomes slightly negative, and the hydrogen atoms become slightly positive. When this happens, we say the molecule is polar.

36
Q

What does having many hydrogen bonds help to do?

A

Stabilise the structure of the molecules

A level Biology - Module 2 (10 decks)

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