Question

A View of Life and its Chemical Basis. 

1. Explain the basic characteristics that are common to all living things. 2. Describe the levels of organization of life. 3. Distinguish among the three domains of life and kingdoms. 4. Explain the process of natural selection. 5. Identify the components of the scientific method. 6. Contrast ionic and covalent bonds. 7. Explain how the properties of water make life possible. 8. Recognize the importance of functional groups in determining the chemical properties of an organic molecule. 9. Summarize the categories of the main macromolecules and provide examples of their diverse biological functions: carbohydrates, lipids, proteins and nucleic acids.

Answer 1

1. Explain the basic characteristics that are common to all living things.

The fundamental characteristics of all living beings are growth, reproduction. All are made up of cells, they adapt and respond to the environment. They all obtain and utilize energy. Though all these are in common, they have different cellular organization.

2. Describe the levels of organization of life.

The various levels of organization of life include organelles, cells, tissues, organs, organ systems, organisms, populations, communities, ecosystem and biosphere. They are in the chronological order starting from the simplest form to the most complex one.

3. Distinguish among the three domains of life and kingdoms.

Three domain system introduced by carl woese divides cellular forms into three domains- archae, bacteria and eukaryotes. It mainly separates archae from prokaryotes based on their 16sRNA differences. This classification is above the kingdom level.

The five kingdom system has prokaryotes without membranes placed under Monera, eukaryotes are placed into 3 kingdoms plantae, fungi and animalia. Protista are a separate kingdom consisting of diversified algae and others which does not come under other groups

4. Explain the process of natural selection

Charles Darwin proposed the natural selection in his theory of evolution. Natural selection is a process by which the organisms which are adapted to the environmental conditions and survive in them. Shortly said as “survival of the fittest”. They transfer the genetic traits to further generations making them more dominant while those who cannot survive get eliminated.

5. Identify the components of the scientific method.

Scientific method is a planned method which helps scientists in answering or solving a problem. It consists of 6 components. 1. Purpose or question of research, 2. Research to find more information on the question, 3. Hypothesis after getting preliminary information, 4. Experimental design of the question, 5. Analysis of the results, 6. Conclusion of the experiment.

6. Contrast ionic and covalent bonds.

Covalent bonds are less polar than ionic bonds.Covalent bond is a chemical bond formed between two non-metals with electronegativities by sharing pair of electrons whereas ionic bond is electrostatic force of attraction between a metal and a nonmetal. Covalent bonds have definite shape wheras ionic doesnot. Covalent bond has low boiling point than ionic bond. Examples for covalent bond are CH4, HCl and for ionic bond are NaCl, H2SO4.

7. Explain how the properties of water make life possible.

Water is the only substance found in liquid at temperatures observed on earth. It is a very good solvent which allows transport of various nutrients to cells and carries waste from them. The hydrogen bonds in the water make it more cohesive than any other liquid. As water molecules are highly polar, they attract each other which helps water to have high surface tension. Water also has high specific heat values and is resistance to change in temperature upto a major extent.

8. Recognize the importance of functional groups in determining the chemical properties of an organic molecule

Functional groups are a part of the molecules which determine the characteristics of the molecule participating in several reactions. They have the ability to characterize the molecules and their chemical properties. In general functional groups comprise of atom or atoms which attribute a particular property to the organic compound. These properties mostly remain same even though the compound changes. Without this group, the compounds may behave differently.

9. Summarize the categories of the main macromolecules and provide examples of their diverse biological functions: carbohydrates, lipids, proteins and nucleic acids.

Four main macromolecules are carbohydrates, lipids, proteins and nucleic acids. They are the components of living bodies playing a vital role in regulating the biochemistry. Carbohydrates are starch and sugars providing instant energy. Lipids are the storage reserves of the energy in the form of long chain fatty acids. Proteins are polypeptides, important for the functioning of cells ad they carry out specific function such as enzymatic activities, receptors. Nucleic acids are the core units of living cells forming the integral structure DNA and RNA which help in regulation of all cellular functions.