Checkpoint 20: DNA & RNA

Which of the following is true about DNA?

• It is only found in animals

• It is only found in plants

• It is found in all living things

• It is found only in bacteria

Answer explanation

DNA is the genetic material found in all living organisms, including animals, plants, and bacteria. Therefore, the correct statement is that it is found in all living things.

Tags

NGSS.MS-LS3-1

Which of the following is NOT a characteristic of DNA?

• Made of two strands

• Contains nucleotides

• Shaped like a cube

• Twisted ladder structure

Answer explanation

DNA is characterized by a double helix structure, made of two strands, contains nucleotides, and has a twisted ladder shape. It is NOT shaped like a cube, making that the correct answer.

Tags

NGSS.MS-LS3-1

The part of the DNA structure described as a "twisted ladder" is the (a)  

• The base pairs
• The double helix
• The single strand
• The nucleotide

Answer explanation

The "twisted ladder" analogy refers to the double helix structure of DNA, where the two strands twist around each other, and the base pairs form the rungs of the ladder. Thus, the correct answer is the double helix.

Match the following DNA bases with their abbreviations.

• Thymine

• A

• Adenine

• T

• Cytosine

• G

• Guanine

• C

Answer explanation

The abbreviation for Thymine in DNA is 'T'. In DNA, the four nucleotides are Adenine (A), Thymine (T), Cytosine (C), and Guanine (G). Therefore, the correct answer is T.

The significance of Chargaff's discovery is that it showed how bases pair in specific (a)   .

• It explained the structure of prote
• It revealed the double helix struct
• It showed how bases pair in specifi
• It discovered the function of RNA.

Answer explanation

Chargaff's discovery showed that in DNA, the bases pair in specific patterns (A with T and C with G). This was crucial for understanding the structure of DNA and its replication, making it a key finding in molecular biology.

Which of the following is a correct base pair according to Chargaff's Rule?

• A-G

• C-T

• A-T

• G-T

Answer explanation

According to Chargaff's Rule, adenine (A) pairs with thymine (T) and cytosine (C) pairs with guanine (G). Therefore, A-T is the correct base pair, while the other options do not follow this pairing rule.

Which of the following is an example of a base pair in DNA?

• A-G

• C-T

• G-C

• T-T

Answer explanation

In DNA, base pairs consist of specific complementary bases. G (guanine) pairs with C (cytosine), making G-C a valid base pair. A-G and C-T are not complementary, and T-T is not a valid pairing.

How often does DNA replication occur?

• Once per day

• Hundreds of times per hour

• Thousands of times per minute

• Millions of times per second

Answer explanation

DNA replication occurs thousands of times per minute in actively dividing cells, ensuring that each new cell receives an accurate copy of the genetic material. This frequency supports rapid growth and tissue repair.

Which enzyme helps in the DNA replication process?

• RNA polymerase

• DNA polymerase

• Helicase

• Ligase

Answer explanation

DNA polymerase is the key enzyme in DNA replication, responsible for synthesizing new DNA strands by adding nucleotides complementary to the template strand. Other enzymes like helicase and ligase play supporting roles.

What is DNA replication compared to in the learning material?

• Building a house

• Solving a puzzle

• Using a template

• Writing a book

Answer explanation

DNA replication is compared to using a template because it involves creating a new strand of DNA based on the existing strand, similar to how a template guides the construction of a new item.

Tags

NGSS.MS-LS3-1