i need help with this qustions for my homework answer the multiple choice that i
ID: 152004 • Letter: I
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i need help with this qustions for my homework answer the multiple choice that is all and be clear not writes un clear stuff just asnswer the qustions please also be correct becaus i need the right answer for my homwork so please help also be correct with the answer becuase i need to study those qustions for my exam so please i need the correct ansers for this qustions important for my TEST
1-Which group of large biological molecules is not synthesized via dehydration reactions?
A- polysaccharides
B- steroids
C- proteins
D- nucleic acids
E- triglycerides
2-Which polysaccharide has branches of alpha 1,4 and alpha 1,6?
A- cellulose
B- chitin
C- amylose
D- amylopectin
E- glycogen
3-Why are human enzymes that digest starch unable to digest cellulose?
A- Cellulose is made of amino-containing sugars that cannot be metabolized.
B- Cellulose has beta-glycosidic linkages; starch-digesting enzymes cleave only alpha-glycosidic linkages.
C- Cellulose has beta-galactoside linkages that only bacterial beta-galactosidases can cleave.
D- Cellulose fibers are covalently cross-linked; starch-digesting enzymes cannot cleave these cross-links.
E- Humans can digest cellulose
4- Which type of biological polymer has the least diversity in properties and structure?
A- Starch
B- polypeptides
C- DNA
D- RNA
5- All lipids
A- are made from glycerol and fatty acids.
B- contain nitrogen.
C- have low energy content.
D- are acidic when mixed with water.
E- do not dissolve well in water.
6- Compared to tropical fish, arctic fish oils have
A- more unsaturated fatty acids.
B- more antifreeze.
C- fewer unsaturated fatty acids.
D- more trans-unsaturated fatty acids.
E- more hydrogenated fatty acids.
7- If actively growing plant cells are given 14C-labeled CO2, what macromolecules will become radioactive first?
A- proteins
B- starch
C- nucleic acids
D- atty acids
8- If you want to selectively label nucleic acids being synthesized by cells, what radioactive compound would you add to the medium?
35S-labeled sulfate
32P-labeled phosphate
135I-labeled leucine
235U-labeled thymidine
Any of these
9- The sickle-cell hemoglobin mutation alters what level(s) of protein structure?
A- primary
B- tertiary
C- quarternary
D- all of the above
E- primary and tertiary structures only
10- Ceviche is prepared by marinating fresh raw fish in citrus juice for several hours, until the flesh becomes opaque and firm, as if cooked. How does citrus juice render the seafood safe to eat?
A- Acidic pH denatures (unfolds and inactivates) proteins by disrupting their hydrogen bonds.
B- Citrus juice denatures proteins by disrupting their ionic bonds.
C- Citrus juice contains enzymes that hydrolyze peptide bonds to break apart proteins.
D- Citrus juice dissolves cell membranes by disrupting hydrophobic interactions.
11-How does RNA differ from DNA?
A- DNA encodes hereditary information; RNA does not.
B- DNA forms duplexes; RNA does not.
C- DNA contains thymine; RNA contains uracil.
D- all of the above
Explanation / Answer
1. B steroids
Everything else is synthesized by dehydration but steroids are synthesized by different pathways from various precursor molecules ex. Cholesterol as precursor of steroid hormones.
2. D,E
As both amylopectin and glycogen have the 1,4 and 1,6 glycosidic bonds but glycogen is more branched.
3. B
As human digestive enzymes can break the alpha glycosidic linkages only but cellulose have beta-1,4-glycosidic linkages betweeen glucose molecules.
4. C Dna
As most probably it is made of amylose and amylopectin ,.polypeptide or proteins, dna used to store genetic information
5. E
Sometimes fatty acids are considered to be simplest form of lipids and many lipids can have fatty acid and other molecules involved,ex. Waxes,steroids etc.
6. A . Asmore unsaturated fatty acids ex omega 3 fatty acid
7. B starch is correct
8. B. 32P may be useused in autorautoradiography of nucleic acid
9. D all
As the mutation cause whole protein structure to change at all levels hence producing nonfunctional protein
10. A .
As the peptide bonds remain intact and hydrogen bonds of secondary protein structure break.
11. C
As there is double stranded rna also and rna is genetic material for many organisms like viruses.
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