Unit 2 - Biological Elements & Water Flashcards Preview

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Flashcards in Unit 2 - Biological Elements & Water Deck (20)
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1
Q

All living things are made primarily from which four key elements?

A

Carbon (C) Hydrogen (H) Oxygen (O) Nitrogen (N)

2
Q

In addition to the four key elements all living things are made primarily from, what other two elements play important roles in the biochemistry of cells ?

A

Phosphorus (P) Sulphur (S)

3
Q

Five cations (+ve ions) that play important roles in organisms

A

Calcium ions (Ca2+) - Nerve impulse transmission and muscle contractions

Sodium ions (Na+) - Nerve impulse transmission and kidney function

Potassium ions (K+) - Nerve impulse transmission and stomatal opening

Hydrogen ions (H+) - Catalysis of reactions, proton pump in photosynthesis, pH determination.

Ammonium ions (NH4+) - Production of nitrate ions

4
Q

Five anions (-ve ions) that play important roles in organisms

A

Nitrate ions (NO3-) - Nitrogen supply to plants for amino acid and protein formation

Hydrogen carbonate ions (HCO3-) - Maintenance of blood pH

Chloride ions (Cl-) - Balance positive charge of sodium and potassium ions in cells

Phosphate ions (PO43-) - Cell membrane formation, nucleic acid and ATP formation, and bone formation

Hydroxide ions (OH-) - Catalysis of reactions, pH determination

5
Q

Which elements are found in carbohydrates?

A

Carbon, hydrogen and oxygen.

6
Q

Which elements are found in lipids?

A

Carbon, hydrogen and oxygen.

7
Q

Which elements are found in proteins?

A

Carbon, hydrogen, oxygen, nitrogen and sulphur.

8
Q

Which elements are found in nucleic acids?

A

Carbon, hydrogen, oxygen, nitrogen and phosphorus.

9
Q

Define the term ‘polar’ in relation to molecules.

A

Molecules that have regions or negativity and regions of positivity

This is due to the way in which electrons are distributed between elements joined by a covalent bond.

10
Q

Explain how polar molecules like water interact with each other.

A

The positive and negative regions of the molecules attract each other and form hydrogen bonds.

These bonds give water its cohesive properties - it moves as one body because the molecules are attracted to each other.

These bonds also give water its adhesive properties - it molecules are attracted to other surfaces.

11
Q

Explain how the ‘skin’ of surface tension of water enables a pond skater to inhabit the surface of water?

A

The skin is caused by water molecules are more strongly cohesive to each other than to air, this skin supports the pond skater.

12
Q

Hydrogen bonds are…

A

Relatively weak interaction that form and break between the constantly moving water molecules.

There are large numbers of then though, which give water its unique characteristic that are essential for life on Earth.

13
Q

What are the unique characteristics of water that are essential for life on Earth?

A
  • Unusually high specific heat capacity (boiling point).
  • Becomes less dense when it freezes.
  • Cohesive properties
  • Adhesive properties
  • ‘Skin’ of surface tension
14
Q

Why is it good that water has a high specific heat capacity?

A

Keeps habitats stable for living things as a lot of energy is needed to change it by a degree.

15
Q

What makes it more difficult for water to become a gas?

A

Hydrogen bonding between molecules

16
Q

Water has a low viscosity. What does this mean?

A

It flows easily

17
Q

Due to water being a liquid at room temp what four things does this allow it to do?

A
  1. Provide a habitat for living things
  2. Form a major component of the tissues in living organisms
  3. Provide a reaction medium for chemical reactions
  4. Provide an effective transport medium
18
Q

Because ice is less dense than water what two things does this allow it to do?

A
  1. Aquatic organisms have a stable environment in which to live throughout the winter
  2. Ponds and other bodies of water are insulated against extreme cold
19
Q

Because water is a good solvent it can do what two things?

A
  1. Molecules and ions can move around and react together in water
  2. Molecules and ions can be transported around living things while dissolved in water
20
Q

How does water dissolve solutes?

A

Water is able to dissolve solutes due to being polar.

  • The negative parts of the water molecules attach to the positive parts of the solute.
  • The positive parts of the water molecules attaches to the negative parts of the solutes.
  • This keeps them away from each other eventually dissolving the solute into a solution.