chemical and cellular basis of life - structured Flashcards
How many elements are recognized in nature?
92 elements
How many elements are essential to continue a healthy life and reproduction?
20-25% of elements
How many elements are essential for humans?
25 elements
How many elements are essential for plants?
17 elements
What elements make up 96% of living matter?
C H O N
What elements make up the remaining 4% of the mass of an organism?
Ca, P, K, and S
What elements are found in minute amounts in living matter?
Co Cu Cr Cl Na Mg B F Fe I
Describe the chemical nature of a water molecule
It is a vital, inorganic, small, polar and angular molecule
state the reasons why life couldn’t exist on this planet without water.
- It is a vital chemical constituent of the living cell
- It provides a biological medium for all organisms
What properties of a water molecule provide the ability to render the vitality?
The physical and chemical properties of a water molecule
What ability do the physical and chemical properties of a water molecule provide?
The ability to render the vitality
Write 3 chemical/physical properties of water
Being a small, polar, and angular molecule
Write the features of a water molecule
Being a small, polar, and angular molecule
How do the properties of water arise?
The properties of water arise due to the hydrogen bonds between different water molecules
What is polarity?
Polarity is the uneven charge distribution within a molecule
Why are water molecules considered “polar”?
In water molecules, the O atom is slightly negative and the H atom is slightly positive, thereby making it polar
What are hydrogen bonds?
Hydrogen bonds are the weak attractions between the slightly polar H atom of one water molecule and the slightly polar O atom of the adjacent molecule
What role do hydrogen bonds play?
Hydrogen bonds play a major role in maintaining all the properties of water
How do the properties of water arise?
They arise due to the hydrogen bonds between different water molecules
Describe the nature of water’s hydrogen bonds
When water is in liquid form, its hydrogen bonds are very fragile. They form, break and reform with great frequency.
Write the major properties of water that helps maintain life on earth?
- Cohesive behavior
- Ability to moderate temperature
- Versatility as a solvent
- Expansion upon freezing
(CAVE)
Write the properties of water related to functions
- Cohesive behavior
- Ability to moderate temperature
- Versatility as a solvent
- Expansion upon freezing
(CAVE)
What is cohesion?
Cohesion is the attraction between water molecules due to hydrogen bonding
What is adhesion?
Adhesion is the attraction between water molecules and other substances
What is the function of both cohesion and adhesion?
Allows water to act as a transport medium
What properties of water allows it to act as a transport medium?
Both the properties of cohesion and adhesion
Write an examples for cohesive behavior
Due to cohesion between water molecules, water and dissolved substances such as minerals and nutrients are transported as a continuous column against gravity.
Water has a high surface tension. This ability is given to water molecules, due to cohesion between the water molecules. In an aquatic system, upper surface water molecules are attracted by lower surface molecules and it forms a water film.
Small insects ( e.g. water skaters ) can walk on the surface of a pond.
Write an example for adhesive behavior
Adhesion between water molecules and cell walls also helps in conduction of water and dissolved substances
Write examples for water’s ability to moderate temperature
Because of high specific heat, water functions as a thermal buffer in living systems and aquatic bodies during temperature fluctuations on earth
Due to the high heat of vaporization, with the minimum loss of water an organism can release much heat energy.
e.g. Therefore, body surface of an organism maintained as cool surface.
Prevent from overheating
Evaporation of sweat from human skin helps to maintain the body temperature at constant level.
Transpiration in plants keeps the plant body surface as a cool surface and prevent from becoming too warm in the
sunlight.
What are the functions of high specific heat?
Because of high specific heat, water functions as a thermal buffer in living systems and aquatic bodies during temperature fluctuations on earth
What is the function of high heat of vaporization?
Because of high heat of vaporization, with the minimum loss of water an organism can release much heat energy.
This helps organisms to cool their body surfaces.
Give examples for high heat of vaporization
This helps organisms cool their body surfaces
Evaporation of sweat from human skin (helps maintain body temperature at a constant level)
Transpiration in plants (helps keep plant body surface cool and prevents from becoming too warm in the sunlight)
What is the function of evaporation of sweat from human skin ?
helps maintain body temperature at a constant level
What is the function of transpiration in plants
helps keep plant body surface cool and prevents from becoming too warm in the sunlight
What substances are transported as a continuous column through xylem against gravity in cohesion
Water
Dissolved substances such as minerals and nutrients
How is the ability of having a high surface tension given to water?
due to the cohesion between water molecules.