Latest Biological Science Reviewer 5 - LET EXAM - Questions & Answers

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Latest Biological Science Reviewer 5


1. Which of the following does NOT belong to the group?

A. Cholesterol
B. Ergosterol
C. Sex hormone
D. Wax

Ans: Cholesterol. Egosterol and sex hormones re example of steroids or steroids containing materials. Cholesterol is the most abundant steroid in the body which serves as a major membrane component . ergosterol is a yeast steroid in that is converted to Vitamin D by ultraviolet radiation. Sex hormones control sexual characteristic and reproduction. Waxes are simple lipids consisting of long chain and a fatty acid joined by esther.

2. Which describes the function of lipids in the body?

A. They regulate heat
B. They provide energy
C. They repair body tissue
D. They contain genetic body tissue

Ans: A. They regulate heat
- The layers of fat under the skin insulate the body when temperature drop too far, layers of fat beneath the skin metabolize to raise them.

3. Which level of protein structure is formed by the twisting and turning of the amino acid chain?

A. Primary structure
B. Secondary structure
C. Teritiary structure
D. Quaternary structure

Ans: B. Secondary structure
- Structural features of proteins are usually characterized at four levels of complexity. Primary structure is the linear arrangement of amino acids forming a polypeptide. Secondary structure is produced by the twist and turns of the amino acid chain. Tertiary structure is the final three-dimensional structure of protein. Quaternary structure is the arrangement of polypeptide chains in a protein that is produced from more than one chain.

4. Which carbohydrate is present in germinating seeds and is a major sugar used in the brewing industry?

A. Fructose
B. Lactose
C. Maltose
D. Sucrose

Ans: C. Maltose
- Maltose is found in beer and is composed of two glucose. It also provides energy in germinating seeds. Fructose or levulose is considered the sweetest among the sugar,being twice as sweet as glucose and is found in fruits, honey, and corn syrups. Sucrose commonly known as table sugar is a combination of glucose and fructose and is considered as an combining glucose and galactose.

5. Gylcogen is to carbohydrates as ____________________.

A. lipid is to fat
B. collagen is to protein
C. nucleic acid is to DNA
D. amino acid is to protein


Ans: B. collagen is to protein
- Glycogen or animal starch is a polysaccharide. Polysaccharide is a type of carbohydrate. Collagen is the most abundant protein in the body. Amino acids are the building blocks of protein in the body. Amino acids the building blocks of protein. DNA is part of nucleic acids.

6. What is the first step in staining a specimen on a microscope slide?

A. Adding chemical fixative
B. Applying an appropriate stain
C. Treating the sample with a surfactant
D. Mounting the sample on a microscope slide


Ans: C. Treating the sample with a surfactant
- The main purpose of staining a specimen on a microscopic slide is to get a better view. Of specimen. The stain usually colors one part of the specimen, but not another part. By creating that color contrast it becomes easier to view parts of the subject. The first step is permeabilization, which is when the sample is treated with a surfactant. This chemical breaks down cell walls and allows in larger molecules of dye.  The next step is fixation where a chemical fixative is added which will create chemical bonds between proteins and enhance their rigidity. The samples must then be mounted on a microscope slide, the samples may be grown directly on the slide. The last step is applying an appropriate stain which color cells, tissues and components.

7. Which biomolecule is composed of nitrogenous base, five carbon sugar and one or more phosphate group?

A. Lipids
B. Lipids
C. Nucleic Acids
D. Protiens

Ans: C. Nucleic Acids
-Nucleotides are the building blocks of nucleic acids. Nucleotides area consist of components covalently bound together 1) a nitrogenous base formed from rings of carbon and nitrogen which may be either a pyrimidine (one ring0 or purine (two rings), 2 a five carbon ring shaped sugar (ribose or deoxyribose), and 3) one two three phosphate groups.

8. How many amino acids and peptide bond’s does a deptide have?

A. 2 amino acids and 1 peptide bonds
B. 2 amino acids and 2 peptide bonds
C. 2 amino acids and 3 peptide bonds 
D. 2 amino acids and 2 peptide bonds

Ans: A. 2 amino acids and 1 peptide bonds
- A peptide bond is a covalent chemical bond linking two consecutive amino acid monomers along a protein chain. Two linked amino acids form a dipeptide; three form a tripeptide; long chains of amino acid are polypeptides.

9. Which correctly describes the two strands of the double helix of the DNA?

A. They are coiled different
B. They are coiled over protein sheath
C. They are coiled around each other
D. They are coiled around a common axis

Ans: D. They are coiled around a common axis
- Double helix is the description of the structure if a DNA molecule. A DNA molecule consist of two strands that wind around each  other like a twisted ladder. The twin rails of the ladder, also known as the sugar-phosphate backbones are alternating units of deoxyribose and phosphate joined with covalent bonds. The two chains are parallel to each other, but they area oriented in opposite directions. Like the northbound and southbound lanes of highway.

10. Irvin wants to appear more muscular aside from going to the gym which of biomolecule must be further added to his diet?

A. Carbohydrates
B, Lipids
C. Nucleic Acids
D. Protiens

Ans: D. Protiens
- Providing your body a contant supply of protein throughout the entire day is necessary for optimum muscle growth. Protien is made up of amino acids. Dietary protein s needed to supply amino acids for growth and maintenance of the body muscles and tissue. Amino acids are the building blocks of protein and play a major role in muscle repair and development of lean body mass.

11. What is fat made of?

A. Alcohol linked by ester bonds to 3 fatty foods
B. Glycerol molecule linked by ester bonds to a fatty acid
C. Glycerol linked by linked by ester bonds to 3 fatty acids
D. Glycerol molecule linked by ester bonds to 4 fatty acids

Ans: C. Glycerol linked by linked by ester bonds to 3 fatty acids
- Fat is subgroup of lipid that is composed of one glycerol bonded to three long hydrocarbon chains (fatty acids) hence, called triglyceride. Enzymes link three fatty acids to one glycerol molecule, yielding three water molecules per triglyceride.

12. Which elements make up carbohydrates?

I. Carbon
II. Hydrogen
III. Nitrogen
IV. Oxygen

A. I, II and III
B. I, II and IV
C. II, III and IV
D. I, II, II and IV

Ans: B. I, II and IV
- Carbohydrates are molecular compounds that consist of carbon, hydrogen and oxygen. The common chemical formula for carbohydrates is Cn(H₂O)n, where the ratios are usually 1 Carbon: 2 Hydrogen: 1 oxygen.

13. Which constitute almost the entire dry weight of nails, claws, beak, horns, wool and large part of the outer layer.

A. Collagen
B. Elastin
C. Fibroin
D. Keratin

Ans: D. Keratin
- Keratin is a protein that forms hair, nails, horns, feathers ans scales. Collagen the most abundant protein in the human body, forms bones, tendons, ligaments and cartilage. Elastin an example is the produced by the silkworm, Bombyx, mori.

14. Which of the following is found in RNA but NOT in DNA?

A. Adenine
B. Phosphate
C. Thymine
D. Uracil

Ans: D. Uracil
- Uracil is one of the four nucleobase in the nucleic acid of RNA. The other three are adenine, guanine and cytosine. In DNA , the uracil nucleobase is replaced by thymine. Uracil I a demethylated form of thymine.

15. At room temperature, saturated fats are in __________ state.

A. sold
B. Liquid
C. gas
D. Semi-liquid

Ans: A. solid
- The state of matter of lipids relates with the structure of fatty acids. Single bonds, as in the case of saturated fats, create a straight molecule, which can be easily packed together to form a solid, while the double bond, as in the case of unsaturated fats introduce a kink in the structure of unsaturated fats ar more like crumple paper.

196. One side of DNA molecule contains AGTCCG sequence of nucleotides. What would be the complementary sequence on the side?

A. GCCTGA
B. TCAGGGC
C. AGTCCG
D. CUGAAU

Ans: B. TCAGGGC
- The structure of DNA consist of two strands of nucleotides that are paired together. One strand of DNA is the template  from which the other one is built. The nitrogenous bases of each nucleotides pair together in specific combination in order to form the structure of DNA. Complementary base pairing is the key to function of the DNA. Cytosin ( C ) bonds only with Guanine (G) while adenine (A) bonds only with thymine (T)

17. Which is responsible in breaking down carbohydrates in its components sugar molecule?

A. Condensation reaction
B. Hydrolysis
C. Glycoside bonding
D. Oxidation

Ans: B. Hydrolysis
- Carbohydrates can be linked together by glycodidic bonds which can be cleaved by hydrolysis. Hydrolysis or saccharification means the cleavage of chemical bonds by the addition of water. This is the key chemical rection in the digestion or starchy foods.

18. A protein chemist would like to arrive at a precise separation of proteins. Which of the following must be conduct?

A. Biuret test
B. Electrophoresis
C. Ninja test
D. Xanthoproteic test

Ans: B. Electrophoresis
- Electrophoresis is considered to be the most precise separation technique available to the proteins chemist. This technique separates proteins on the basis of a difference in size and a difference in charge. It operates on the principle that charge particles move in an electric field. Protein electrophoresis is used to identify the presence of abnormal proteins to identify the absence of normal proteins, and to determine when different groups of proteins are present in usually high or low amounts in blood or other body fluids. The biuret test is a chemical test used for detecting the presence of peptide bonds. Ninhydrin is an extremely sensitive reagent for amino acids. The xanthoproteic test using concentrated nitric acid.

19. Which is the first step of gene expression, in which a particular segment of DNA is copied into m RNA by  enzyme RNA polymerase?

A. Imitation
B. Elongation
C. Transcription
D. Translation

Ans: C. Transcription
- The biosynthesis of RNA is called transcription. When the nucleotides sequence of one strands of DNA is transcribed into a single strand RNA , genetic information is copied from DNA to RNA. It proceeds in much the same fashion as the replication of DNA an as follows the basic pairing principle. Translation is production of a polypeptide.

20. Which is TRUE about polymerization reactions in which proteins area synthesized from amino acids?

A. The release energy
B. They are hydrolysis reactions
C. They result in the formation of water
D. They result in the formation of peptide bonds

Ans: C. They result in the formation of water
- Proteins and polyeptides are to be found in living organisms. Polypeptides are formed by condensation polymerization reaction between two amino acids. These two amino acids by a peptide link and realse a water molecule.

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