Question

QUESTION 1

1. Protein secondary structure is maintained by __________ bonds and protein tertiary structure is maintained by _____________

   	1.	Ionic: Covalent bonds
   	2.	Hydrogen: R group interactions
   	3.	R group interactions; hydrogen bonds
   	4.	ionic bonds; R group interactions

10 points   

QUESTION 2

1. Humans (Homo sapiens) have existed in their current form for around _______ years, and agriculture began about ____ years ago

   	1.	50,000; 20,000
   	2.	200,000; 10,000
   	3.	100,000; 2,000
   	4.	500,000; 10,000

10 points   

QUESTION 3

1. Water has many unusual and important characteristics that make it a requirement for life to exist as we know it. What best explains the ultimate reasons for these characteristics? That is, what is the underlying reason that explains all the other things about water that we talk about as being required for life?

   	1.	Water is electronegative
   	2.	Water is a polar molecule, and the hydrogen atoms are electronegative
   	3.	the Oxygen atom in water has 8 protons compared to 1 in each in the Hydrogens atoms
   	4.	The Hydrogens in the water molecule are electronegative, conferring polarity to the molecule

10 points   

QUESTION 4

1. The dramatic increase in the burning of fossil fuels, among other things, has led to

   	1.	an increase in ocean pH
   	2.	an increase in ocean OH- concentration
   	3.	lower ocean temperatures
   	4.	an increase in ocean H+ concentration

10 points   

QUESTION 5

1. In the periodic table of elements, Silicon (element number 14) is in the same column and directly below Carbon (element number 6). This means that Silicon

   	1.	Has the same number of electrons as Carbon
   	2.	Has the same number of valence electrons as Carbon
   	3.	Has the same number of protons as Carbon
   	4.	Has the same number of neutrons as Carbon

10 points   

QUESTION 6

1. Adventures in the Anthropocene, Ch 3:Rivers, talks a lot about Patagonia. Where is Patagonia?
   

   		Southern South America
   		Northern South America
   		Western Europe
   		Nepal

10 points   

QUESTION 7

1. Decomposers, especially bacteria, are extremely important in which nutrient cycle?

   	1.	Carbon
   	2.	Oxygen
   	3.	Nitrogen
   	4.	water (hydrological cycle)

10 points   

QUESTION 8

1. Elephants and whales exhibit a Type ___ survivorship curve, while oysters and shrimp exhibit a Type ____ survivorship curve

   	1.	I;III
   	2.	II;III
   	3.	III:II
   	4.	III;I

10 points   

QUESTION 9

1. In general we can say that organisms that have a Type III survivorship curve usually have ___ selected traits and that large, long lived organisms with delayed reproduction have __ selected traits

   	1.	competetive;non-competetive
   	2.	K;r
   	3.	r;K
   	4.	S;R

10 points   

QUESTION 10

1. What percent of the water on the surface of Earth (excluding water vapor or clouds) is "fresh" water (non-salt water)?

   	1.	20%
   	2.	10%
   	3.	5%
   	4.	2.5%

Answer 1

Ans.1. Option ( 2) is the CORRECT answer.

Rrason :- 1.Secondary structure of proteins is maintained by hydrogen bonds because secondary structure in terms of bonds is defined by the pattrern of hydrogen bonds between the amino hydrogen and carboxyl oxygen atoms in the peptide backbone.

Due to the regular folding of backbone of peptide chain two types of secondary structure arises which are:-

a) Alpha helix structure : In this a polypeptide chain forms all possible hydrogen bonds by twisting into a right handed screw (helix) with the -NH group of each amino acid residue hydrogen bonded to the >C=O of an adjacent turn of helix.

b) Beta pleated sheet structure :In this all peptide chain stretched out to nearly maximum extension and then laid side by side which are held together by intermolecular hydrogen bonds.

2.Tertiary structure:- It represents the overall folding of the polypeptide chains by further folding secondary structure.Actually this structure is formed primarily due to interactions between the R groups of amino acids that make up the protein.R group interactions that contribute to the tertiary structure include hydrogen bonding,ionic bonding,dipole-dipole interactions,etc.

Hydrophobic interactions are also important  in which amino acid with non polar,hydrophobic R groups cluster together on the inside of the protein,leaving hydrophilic amino acids on the outside to interact with the surrounding water molecules.

Bonding of tertiary structure gives two molecular shapes to tertiary structure:

a)Globular structure

b)Fibrous structure.