Basics Of Biology And Chemistry

Question 1

Explain the place of biology within the discipline of science.

Answer 1

Biology is the science that study live.

Question 2

Describe properties common to all life. Explain why cells are a special level in biological organisation.

Answer 2

All lives share 5 characteristics:

• Energy processing ( methobolism it can make reactions that creates energy)
• Regulation of internal environment: Temperature, Oxygène … they maintaine constante internal conditions regardless of the environment
• Reproduce, grow
• Evolves over time. It’s can be a result of mutations and random changes in the genetic material. This can help the living to live better in the
• adapt to it’s environment
• Celles-> smallest units of live. It has all the previous characteristics (ex of plants)

Celles are limited by a membran so the celle fully control what’s going on inside it. It creates energy. Interacts with the external environment through for instance stoma.

Question 3

Compare ionic,hydrogen, and covalent bonds, and contrast between polar and non-polar.

Answer 3

Ionic bond: if you have two atomes, on is going to take one or many electrons from the other.
Covalent bond the two atomes are sharing an electron.
Hydrogèn bond. The hydrogène is going to share electron with another atome H2O

A molecule is polar when it’s atomes have diferent partial charges. That means the difference between their electronegativity is quite large.

A molecule is non polar when it s atomes the same partial charge and the difference bet their electrogvity is small.

Question 4

Distinguish between hydrophilic and hydrophobic and describe their interations.

Answer 4

A substance is hydrophilic I’d it dissolves in water-> hydrogens bonds will be formed. H in water is attracted to the atome(s) of the substance. Hydrophilic substances are polar.

A substance is hydrophobic if doesn’t dissolves in water hydrogène bonds cannot be formed ex oil. This substance are in general non polar

Question 5

Describe the properties of water and relate them to the molecular structure of water.

Discuss how these properties of water benefits organisms and why are they considered life -supporting properties.

Answer 5

All lives are water-based-> it cannot live without it ex water is necessary to keep us hydrated it s an essential reactant

• Water stabilizes temperature
As the motion of water molecules goes up, T and Energy ++ -> Water absorbes an importante amount of energy befor it s T ++ ->
Important energy disturb the hydrogène bonds between water molecules ->
Then at some point there will be E++++ lots of hydrogène bonds will be destructed -> evaporation

Because water absorb energy and it s T change only a bit -> water moderate T within organisms
The evaporation of water-> cold down organism ( the destructation of H bonds takes a lots of energy so organisms need to cold down)

•Water is a good solvent
Because h2o is polar it dissolves ionic compounds. H forms a hydration shell around -ions and O is attracted to + ion. Water separate ions compounds.

• Cohesion property of water

Cohesion is the attraction between same molecules like H2O-> it sticks together ( water is polar)
At the interface between water and air. H2O molecules have stronger bonds between them than they have with air molecules -> creat à tension surface-> the water surface does not break when placed under pressure -

This explaines how droplet are formed, some insects like pound-skaters stay on top of water surface -> habitat

Question 6

PH

ACIDE BASE

Answer 6

Ph =-log[H+]