大学MOOC Basic Biochemistry(Northwest A&F University)1461613176 最新慕课完整章节测试答案

Test for Chapter 2

1、单选题：
‎After the complete hydrolysis of DNA and RNA, the characteristics of its products are:​
选项：
A: Different pentoses and different bases.
B: Different pentoses and the same bases.
C: The same pentose and the same base.
D: The same pentose and different base.
答案: 【 Different pentoses and different bases.】

2、单选题：
‍The connection between nucleotides in nucleic acid molecules is:‍
选项：
A: 3′,3′,-phosphodiester bond.
B: Glycosidic bond.
C: 3′,5′-phosphodiester bond.
D: Peptide bond.
答案: 【 3′,5′-phosphodiester bond.】

3、单选题：
‏The key parts of storing and transmitting genetic information in nucleic acid molecules are:​
选项：
A: Nucleoside
B: Pentose
C: Phosphate
D: Base sequence
答案: 【 Base sequence】

4、单选题：
‌The secondary structure of DNA refers to:‌
选项：
A: α-helix 
B: β-sheet
C: β-turn
D: Double helix structure
答案: 【 Double helix structure】

5、单选题：
‍Which of the following nucleic acids has a "clover" type secondary structure?‍
选项：
A: mRNA
B: Plasmid DNA 
C: tRNA 
D: Mitochondrial DNA
答案: 【 tRNA 】

6、单选题：
‏ After double-stranded DNA thermal denaturation‏
选项：
A: Decrease in viscosity
B: Decrease in sedimentation coefficient
C: Decrease in buoyancy density
D: Decrease in UV absorption
答案: 【 Decrease in viscosity】

7、单选题：
​The higher DNA Tm value is due to the higher nucleotide content of the following group?‌
选项：
A: G+A 
B: C+G
C: A+T
D: C+T
答案: 【 C+G】

8、单选题：
‎The main force that maintains the stability of the DNA double helix is‌
选项：
A: Hydrogen bond
B: Ionic bond
C: Base accumulation force
D: Van der Waals
答案: 【 Base accumulation force】

9、单选题：
‍A pure double-stranded DNA sample contains 15% A, and the content of G in this sample is‌
选项：
A: 35% 
B: 15% 
C: 30% 
D: 20%
答案: 【 35% 】

10、单选题：
‍According to the Watson-Crick model, the average number of nucleotide pairs per micron DNA double helix is: ‍
选项：
A: 25400
B: 2540
C: 29411
D: 2941
答案: 【 2941】

11、单选题：
The main force that maintains the stability of the DNA double helix is ‌
选项：
A: Hydrogen bond
B: Ionic bond
C: Base accumulation force
D: Van der Waal
答案: 【 Base accumulation force】

12、多选题：
​Which of the following statements about the Watson-Crick DNA double helix structure model is wrong?‌
选项：
A: The direction of the two single chains is anti-parallel
B: Base A and G pair
C: Covalent bonding between bases
D: The pentose phosphate backbone is located inside the double helix.
答案: 【 Base A and G pair;
Covalent bonding between bases;
The pentose phosphate backbone is located inside the double helix.】

13、多选题：
​Which of the following statements about nucleic acids is correct:​
选项：
A: DNA is the carrier of genetic material, responsible for the storage, transmission and release of genetic information; RNA is responsible for the expression of genetic information.
B: Nucleic acid mainly exists in the nucleus
C: Nucleic acid is divided into DNA and RNA.
D: All organisms contain both DNA and RNA nucleic acids.
答案: 【 DNA is the carrier of genetic material, responsible for the storage, transmission and release of genetic information; RNA is responsible for the expression of genetic information.;
Nucleic acid mainly exists in the nucleus;
Nucleic acid is divided into DNA and RNA.】

14、多选题：
Regarding the type and distribution of RNA, which of the following statements is correct (       )‏
选项：
A: RNA is mainly found in the nucleus.
B: mRNA accounts for about 5% of the total RNA of the cell and serves as a template in protein synthesis
C: rRNA accounts for 80% of the total RNA of the cell, is a component of the ribosome, and is a place for protein synthesis.
D: tRNA accounts for 10-15% of the total RNA of the cell, and plays the role of carrying activated amino acids in protein synthesis.
答案: 【 mRNA accounts for about 5% of the total RNA of the cell and serves as a template in protein synthesis;
rRNA accounts for 80% of the total RNA of the cell, is a component of the ribosome, and is a place for protein synthesis.;
tRNA accounts for 10-15% of the total RNA of the cell, and plays the role of carrying activated amino acids in protein synthesis.】

15、多选题：
 Which of the following statements is wrong‌
选项：
A:  Z-DNA segment exists in the natural DNA molecule.
B: The interaction between B-DNA and Z-DNA may be related to gene regulation.
C:  A-DNA, B-DNA, C-DNA and Z-DNA are all right-handed helices.
D: Z-DNA axis passes through base pairs
答案: 【 The interaction between B-DNA and Z-DNA may be related to gene regulation.;
Z-DNA axis passes through base pairs】

16、多选题：
The products produced by the complete hydrolysis of nucleic acids are‌
选项：
A: Base
B: Ribose
C: Phosphoric acid
D: Nucleotide
答案: 【 Base;
Ribose;
Phosphoric acid】

17、多选题：
Which of the following statements are correct ‍
选项：
A: Nucleic acid molecule is mainly composed of carbon, hydrogen, oxygen, nitrogen, sulfur and phosphorus
B: The base composition of DNA and RNA differs in the composition of pyrimidines.
C: Contains a small amount of other unusual bases in DNA and RNA molecules, called rare bases. Most of them are methylated derivatives of common bases.
D: Dehydration between base and ribose or deoxyribose through condensation of glycosidic bond to form nucleoside or deoxynucleoside.
答案: 【 The base composition of DNA and RNA differs in the composition of pyrimidines.;
Contains a small amount of other unusual bases in DNA and RNA molecules, called rare bases. Most of them are methylated derivatives of common bases.;
Dehydration between base and ribose or deoxyribose through condensation of glycosidic bond to form nucleoside or deoxynucleoside.】

18、多选题：
8 Which of the following related statements is correct ‏
选项：
A: The 1st carbon atom of pentose is connected to the 9th nitrogen atom of purine to form a l,9-glycosidic bond.
B: Dehydration between the free hydroxyl group of pentose sugar in nucleoside and phosphoric acid generates nucleotides through condensation of phosphoester bond
C: Both deoxyribonucleoside and ribonucleoside can form 2'-3'- or 5'-ribonucleotide
D: 5'-nucleotides are mostly free in organisms.
答案: 【 The 1st carbon atom of pentose is connected to the 9th nitrogen atom of purine to form a l,9-glycosidic bond.;
Dehydration between the free hydroxyl group of pentose sugar in nucleoside and phosphoric acid generates nucleotides through condensation of phosphoester bond;
5'-nucleotides are mostly free in organisms.】

19、多选题：
Which of the following statements are correct ‌
选项：
A: Nucleotides are connected to each other by 3', 5'-phosphodiester bond to form a polynucleotide chain.
B: The bond between pentose and phosphat is called a phosphodiester bond because one phosphate group forms two ester bonds.
C: Both the DNA strand and the RNA strand have two free ends. The end with a free phosphate group on the 5-position carbon of the pentose of the nucleotide residue is called the 5′ end, and the 3-position carbon of the pentose has One end of the free hydroxyl group is called the 3'end.
D: The polynucleotide chain is composed of sugar-phosphate and the base is inside the skeleton.
答案: 【 Nucleotides are connected to each other by 3', 5'-phosphodiester bond to form a polynucleotide chain.;
The bond between pentose and phosphat is called a phosphodiester bond because one phosphate group forms two ester bonds.;
Both the DNA strand and the RNA strand have two free ends. The end with a free phosphate group on the 5-position carbon of the pentose of the nucleotide residue is called the 5′ end, and the 3-position carbon of the pentose has One end of the free hydroxyl group is called the 3'end.;
The polynucleotide chain is composed of sugar-phosphate and the base is inside the skeleton.】

20、多选题：
Which of the following statements are correct​
选项：
A: In the tRNA molecule, A contains rare bases in addition to the four basic bases (A, G, C, U).
B: The DNA of all somatic cells of an organism has the same base composition, and this base composition can be used as the species characteristics.
C: Nucleic acid probe refers to a single strand of nucleic acid with a label.
D: DNA is genetic material, but RNA is not.
答案: 【 In the tRNA molecule, A contains rare bases in addition to the four basic bases (A, G, C, U).;
The DNA of all somatic cells of an organism has the same base composition, and this base composition can be used as the species characteristics.;
Nucleic acid probe refers to a single strand of nucleic acid with a label.】

21、多选题：
What happens after double-stranded DNA is heat denatured:‏
选项：
A: Decreased viscosity 
B: Decreased settlement coefficient
C: Decreased buoyancy density
D: Decreased UV absorption
答案: 【 Decreased viscosity ;
Decreased settlement coefficient;
Decreased buoyancy density】

22、多选题：
The factors that affect the Tm value are: ‍
选项：
A: The longer the nucleic acid molecule under certain conditions, the larger the Tm value
B: The content of G and C in DNA is high, the Tm value is high
C: Solution has high ionic strength, Tm value is high
D: High content of A and T in DNA, high Tm v