VELAMMAL BODHI CAMPUS - ANUPPANADI
XII -BIOMOLECULES
WORK SHEET
Choose the best
1.Which biomolecule is distributed more widely in a cell?
A)Chloroplast b) RNA c)DNA d) Spaherosomes
2. Which is a reducing sugar?
A)Galactose b)Gluconic acid c)Sucrose d) β-methyl galactosidase
3. Most abundant RNA in the cell
A)rRNA b)mRNA c)tRNA d)tRNA threonine
4. Name the simplest amino acid
A)Alanine b) Tyrosine c)Asparagine d) Glycine
5. Mineral associated with cytochrome is
A)Mg b) Cu and Ag c)Fe d) Cu
6. The most common secondary structure of proteins is
A)β-pleated sheet b)β-pleated sheet parallel c) β-pleated sheet non-parallel
D)α-helix
7. The term enzyme was coined by
A)Urey Miller b)Pasteur c)Kuhne d) Buchner
8. β-oxidation occurs in
A)Nucleus b) Cytoplasm c)Mitochondria d) Chloroplast
9. Koshland’s theory of enzyme action is known as
A)Lock and key theory b)Reduced fit theory c) Induced fit theory
D)Enzyme coenzyme theory
10. A high content of triglycerides are found in
A)VLDL b) LDL c) HDL d)Chylomicrons
11. Haemoglobin has
A)Primary structure b)Secondary structure c)Tertiary structure
D)Quaternary structure
12. Which is the most abundant biomolecule on earth?
A)Mineral salts b)Proteins c) Lipids d)Carbohydrates
13. In which of the following an anticodon occurs
A)tRNA b)mRNA c)rRNA d)DNA
14. The fastest enzyme is
A)DNA gyrase b)Pepsin c) DNA polymerase d)Carbonic anhydrase
15. Which of the following is a phospholipid?
A)Sterol b)Cholesterol c)Lecithin d)Steroid
Case Study
Read the passage given below and answer the following questions:
Pentose and hexose undergo intramolecular hemiacetal or hemiketal formation due to combination of the -OH
group with the carbonyl group. The actual structure is either of five or six membered ring containing an oxygen
atom. In the free state all pentoses and hexoses exist in pyranose form (resembling pyran). However, in the
combined state some of them exist as five membered cyclic structures, called furanose (resembling furan).
The cyclic structure of glucose is represented by Haworth structure:
αα and ββ -D-glucose have different configuration at anomeric (C-l) carbon atom, hence are called anomers and
the C-l carbon atom is called anomeric carbon (glycosidic carbon).
The six membered cyclic structure of glucose is called pyranose structure.
Answer the following
(i) αα -D(+)-glucose and ββ -D( +)glucose are
(ii) The following carbohydrate is
(iii) In the following structure, anomeric carbon is
(iv) The term anomers of glucose refers to
Read the passage given below and answer the following questions:
When a solution of an αα -amino acid is placed in an electric field depending on the pH of the medium, following
three cases may happen.
(i) In alkaline solution,αα -amino acids exist as anion II, and there is a net migration of amino acid towards the
anode.
(ii) In acidic solution, αα -amino acids exist as cation III, and there is a net migration of amino acid towards the
cathode.
(iii) If II and III are exactly balanced there is no net migration; under such conditions anyone molecule exists as a
positive ion and as a negative ion for exactly the same amount of time, and any small movement in the direction
of one electrode is subsequently cancelled by an equal movement back toward the other electrode. The pH of the
solution in which a particular amino acid does not migrate under the influence of an electric field is called the
isoelectric point of that amino acid.
Answer the following questions.
I)In aqueous solutions, amino acids mostly exist as
(ii)Amino acids are least soluble at
(iii) The pKa1 and pKa2 of an amino acids are 2.3 and 9.7 respectively. The isoelectric point of the amino acid is
Read the passage given below and answer the following questions:
Carbohydrates are polyhydroxy aldehydes and ketones and those compounds which on hydrolysis give such
compounds are also carbohydrates. The carbohydrates which are not hydrolysed are called monosaccharides.
Monosaccharides with aldehydic group are called aldose and those which free ketonic groups are called ketose.
Carbohydrates are optically active. Number of optical isomers = 2n
Where n = number of asymmetric carbons. Carbohydrates are mainly synthesised by plants during
photosynthesis.
The monosaccharides give the characteristic reactions of alcohols and carbonyl group (aldehydes and ketones).
It has been found that these monosaccharides exist in the form of cyclic structures. In cyclization, the -OH groups
(generally C5 or C4 in aldohexoses and C5 or C6 in ketohexoses) combine with the aldehyde or keto group. As a
result, cyclic structures of five or six membered rings containing one oxygen atom are formed, e.g., glucose forms
a ring structure. Glucose contains one aldehyde group, one 1o alcoholic group and four 2o alcoholic groups in its
open chain structure.
(i) First member of ketos sugar is
(ii) In CH2OHCHOHCHOHCHOHCHOHCHO, the number of optical isomers will be
(iii) Some statements are given below:
1. Glucose is aldohexose.
2. Naturally occurring glucose is dextrorotatory.
3. Glucose contains three, chiral centres.
4. Glucose contains one 1o alcoholic group and four 2o alcoholic groups.
Among the above, correct statements are
(a) 1 and 2 only (b) 3 and 4 only (c) 1,2 and 4 only ( d) 1,2,3 and 4
(iv) Which of the following reactions of glucose can be explained only by its cyclic structure?
a) Glucose forms cyanohydrin with HCN
b) Glucose reacts with hydroxylamine to form an oxime
c) Pentaacetate of glucose does not react with hydroxylamine
d) Glucose is oxidised by nitric acid to gluconic acid .
Assertion and reason questions
Assertion : Polysaccharides are called non-sugars.
Reason : Carbohydrates which yield a large number of monosaccharide units on hydrolysis are called
polysaccharides.
Assertion : Maltose and lactose are examples of reducing sugars.
Reason : Maltose and lactose reduce Fehling’s solution and Tollens’ reagent.
Assertion : Glucose gets oxidised to gluconic acid on reaction with mild oxidising agent like bromine water.
Reason : Glucose contains a keto group.
Assertion : Glucose is correctly named as D-(+)-glucose. ' 3
Reason : ‘D’ before the name of glucose represents its dextrorotatory nature.
Assertion : D-glucose is dextrorotatory whereas L-glucose is laevorotatory.
Reason : D-compounds are always dextro and L-compounds are always laevorotatory
Assertion : Glucose reacts with phenyl hydrazine and Fehling's solution but not with NaHSO3.
Reason: NaHSO3 cannot break the ring structure.
Assertion: Sucrose is a non reducing sugar.
Reason : Sucrose is a disaccharide formed by glycosidic linkage between C-1 of α-glucose and C-2 of β-fructose.
Assertion: All naturally occuring α-amino acids are optically active
Reason: Most naturally occuring amino acids have D-configuration.
Assertion: All enzymes found in cells are invariably proteins which catalyse biological reactions.
Reason : Enzymes act efficiently at a moderate temperature and pH.
