Question 1:

The genetic code is considered universal because, with only minor exceptions, the same codons (triplets of DNA or RNA bases) code for the same amino acids in all living organisms, from bacteria to humans. This means that a specific sequence of DNA that codes for an amino acid in a plant will also code for the same amino acid in an animal. 🧬

This universality is one of the strongest pieces of evidence for the theory of universal common descent, which states that all life on Earth shares a single, common ancestor. It is highly improbable that the exact same arbitrary genetic code would have evolved independently in separate lineages. Instead, the shared code suggests it was inherited from the first living organism and has been conserved throughout evolutionary history.

The correct answer is B. all life forms have common ancestry.

*These A.I. responses have been individually checked to ensure they match the accepted answer, but explanations may still be incorrect. Responses may give guidance but the A.I. might not be able to answer the question! This is particularly the case for questions based on diagrams, which the A.I. typically cannot interpret.
Grade Gorilla uses Gemini, Deepseek and a range of other A.I. chatbots to generate the saved responses. Some answers have had human intervention for clarity or where the A.I. has not been able to answer the question.

Question 2:

The backbone of a DNA strand is a repeating sequence of deoxyribose sugars and phosphate groups, linked together by strong phosphodiester bonds. The nitrogenous bases (adenine, guanine, cytosine, and thymine) attach to the deoxyribose sugars and extend inwards, forming the "rungs" of the DNA ladder.

The correct answer is B. Deoxyribose and phosphate.

*These A.I. responses have been individually checked to ensure they match the accepted answer, but explanations may still be incorrect. Responses may give guidance but the A.I. might not be able to answer the question! This is particularly the case for questions based on diagrams, which the A.I. typically cannot interpret.
Grade Gorilla uses Gemini, Deepseek and a range of other A.I. chatbots to generate the saved responses. Some answers have had human intervention for clarity or where the A.I. has not been able to answer the question.

Question 3:

The nitrogenous bases that make up the "rungs of the ladder" in DNA follow specific base-pairing rules:

Adenine (A) always pairs with Thymine (T).

Guanine (G) always pairs with Cytosine (C).

Uracil (U) is not found in DNA. It is a base found in RNA (Ribonucleic Acid), where it pairs with Adenine in place of Thymine.

The correct answer is C. Uracil – Adenine.

*These A.I. responses have been individually checked to ensure they match the accepted answer, but explanations may still be incorrect. Responses may give guidance but the A.I. might not be able to answer the question! This is particularly the case for questions based on diagrams, which the A.I. typically cannot interpret.
Grade Gorilla uses Gemini, Deepseek and a range of other A.I. chatbots to generate the saved responses. Some answers have had human intervention for clarity or where the A.I. has not been able to answer the question.

Question 4:

Let's analyze the question: "The bases in DNA are joined to ..."

In DNA, the nitrogenous bases (adenine, guanine, cytosine, thymine) are attached to the deoxyribose sugar. Specifically, the base is linked to the 1' carbon of the deoxyribose sugar via a glycosidic bond. The deoxyribose sugar is part of the nucleotide, and the sugar itself is connected to the phosphate group.

Now, looking at the options:
A. phosphorous – Bases are not directly joined to phosphorus. Phosphorus is in the phosphate group, which is attached to the sugar, not the base.
B. oxygen – Oxygen is abundant in the sugar and phosphate, but the base is not directly joined to oxygen; the glycosidic bond is between the base and the carbon of the sugar.
C. hydrogen – Hydrogen bonds hold the two strands together (base pairing), but the bases are not joined to hydrogen within the nucleotide.
D. carbon – The base is attached to the 1' carbon of the deoxyribose sugar via a nitrogen-carbon glycosidic bond.

Therefore, the correct answer is that the bases are joined to carbon. D

*These A.I. responses have been individually checked to ensure they match the accepted answer, but explanations may still be incorrect. Responses may give guidance but the A.I. might not be able to answer the question! This is particularly the case for questions based on diagrams, which the A.I. typically cannot interpret.
Grade Gorilla uses Gemini, Deepseek and a range of other A.I. chatbots to generate the saved responses. Some answers have had human intervention for clarity or where the A.I. has not been able to answer the question.

Question 5:

The complementary bases in DNA (e.g., adenine with thymine, and guanine with cytosine) are held together by hydrogen bonds. Specifically:
- Adenine and thymine form two hydrogen bonds.
- Guanine and cytosine form three hydrogen bonds.

These hydrogen bonds provide the specificity for base pairing and help stabilize the double helix structure.

Now, evaluating the options:
- A. Polar: This refers to bonds with unequal sharing of electrons (like in covalent bonds with electronegativity differences), but it is not the primary bond for base pairing.
- B. Hydrogen: Correct, as explained.
- C. Covalent: Covalent bonds are strong and found within nucleotides (e.g., between the base and sugar, or sugar and phosphate), but not between complementary bases.
- D. Peptide: Peptide bonds are specific to proteins, linking amino acids.

Thus, the complementary bases in DNA are linked by hydrogen bonds. Answer B

*These A.I. responses have been individually checked to ensure they match the accepted answer, but explanations may still be incorrect. Responses may give guidance but the A.I. might not be able to answer the question! This is particularly the case for questions based on diagrams, which the A.I. typically cannot interpret.
Grade Gorilla uses Gemini, Deepseek and a range of other A.I. chatbots to generate the saved responses. Some answers have had human intervention for clarity or where the A.I. has not been able to answer the question.

Question 6:

The diagram likely shows a structure with three components: a nitrogenous base, a pentose sugar, and a phosphate group. This is characteristic of a nucleotide.

A nucleoside consists only of a base attached to a sugar (no phosphate).

DNA or RNA would be larger polymers, not just a single unit.
Thus, the diagram represents a nucleotide.

Answer for Question 6: B

*These A.I. responses have been individually checked to ensure they match the accepted answer, but explanations may still be incorrect. Responses may give guidance but the A.I. might not be able to answer the question! This is particularly the case for questions based on diagrams, which the A.I. typically cannot interpret.
Grade Gorilla uses Gemini, Deepseek and a range of other A.I. chatbots to generate the saved responses. Some answers have had human intervention for clarity or where the A.I. has not been able to answer the question.

Question 7:

The three structures (base, sugar, phosphate) are held together by covalent bonds:

The base is attached to the sugar via a glycosidic bond (covalent).

The sugar is attached to the phosphate via a phosphoester bond (covalent).
Polar bonds are not a primary bond type in this context, hydrogen bonds are for base pairing between strands, and peptide bonds are for proteins.

Answer for Question 7: C

*These A.I. responses have been individually checked to ensure they match the accepted answer, but explanations may still be incorrect. Responses may give guidance but the A.I. might not be able to answer the question! This is particularly the case for questions based on diagrams, which the A.I. typically cannot interpret.
Grade Gorilla uses Gemini, Deepseek and a range of other A.I. chatbots to generate the saved responses. Some answers have had human intervention for clarity or where the A.I. has not been able to answer the question.

Question 8:

Let's evaluate the options for RNA based on its correct characteristics:

Sugar: RNA contains ribose sugar (not deoxyribose).

Bases: RNA uses adenine (A), cytosine (C), uracil (U), and guanine (G). It does not use thymine (T); thymine is replaced by uracil in RNA.

Number of strands: RNA is typically single-stranded (one strand), unlike DNA which is double-stranded.

Now, check each option:

Option A:

Sugar: Ribose ✅

Bases: A, C, U, G ✅ (uracil instead of thymine)

Strands: One ✅
This is correct for RNA.

Option B:

Sugar: Ribose ✅

Bases: A, C, T, G ❌ (has thymine instead of uracil)

Strands: One ✅
Incorrect bases.

Option C:

Sugar: Deoxyribose ❌ (should be ribose)

Bases: A, C, U, G ✅

Strands: Two ❌ (RNA is single-stranded)
Incorrect sugar and number of strands.

Option D:

Sugar: Deoxyribose ❌

Bases: A, C, T, G ❌

Strands: Two ❌
Completely incorrect for RNA.

Therefore, only Option A is correct.

*These A.I. responses have been individually checked to ensure they match the accepted answer, but explanations may still be incorrect. Responses may give guidance but the A.I. might not be able to answer the question! This is particularly the case for questions based on diagrams, which the A.I. typically cannot interpret.
Grade Gorilla uses Gemini, Deepseek and a range of other A.I. chatbots to generate the saved responses. Some answers have had human intervention for clarity or where the A.I. has not been able to answer the question.

Question 9:

To determine the correct complementary base pairing for DNA, recall the standard base pairs:

Adenine (A) pairs with Thymine (T)

Cytosine (C) pairs with Guanine (G)

The given sequence is:
A C T G G T A

Now, let's find its complementary strand:

A → T

C → G

T → A

G → C

G → C

T → A

A → T

So, the complementary strand should be:
T G A C C A T

Now, compare this with the options:

Option A:

Complementary: T A G C C U T
❌ Incorrect because:

Second base should be G (to pair with C), but it is A.

Third base should be A (to pair with T), but it is G.

Sixth base should be A (to pair with T), but it is U (uracil is not in DNA; it is for RNA).

Option B:

Complementary: T G A C C A T
✅ This matches exactly the expected complementary strand.

Option C:

Complementary: U G A C C A U
❌ Incorrect because it uses U (uracil) instead of T. DNA does not have uracil.

Option D:

Complementary: G T C A A C G
❌ Incorrect because:

First base should be T (to pair with A), but it is G.

Second base should be G (to pair with C), but it is T.

And so on.

Therefore, Option B is correct.

*These A.I. responses have been individually checked to ensure they match the accepted answer, but explanations may still be incorrect. Responses may give guidance but the A.I. might not be able to answer the question! This is particularly the case for questions based on diagrams, which the A.I. typically cannot interpret.
Grade Gorilla uses Gemini, Deepseek and a range of other A.I. chatbots to generate the saved responses. Some answers have had human intervention for clarity or where the A.I. has not been able to answer the question.

Question 10:

The correct representation is C. 5′ → 3′ and 3′ ← 5′.

The two strands of a DNA double helix are described as antiparallel because they run in opposite directions. Each strand has a distinct chemical polarity, with one end known as the 5' end and the other as the 3' end.

• The 5' end is characterized by a phosphate group attached to the fifth carbon atom of the deoxyribose sugar.

• The 3' end is characterized by a hydroxyl group attached to the third carbon atom of the deoxyribose sugar.

For the two strands to form a stable double helix and allow for complementary base pairing (A with T, G with C), they must be oriented in opposite directions. If one strand is oriented in the 5' to 3' direction, its complementary partner must be oriented in the 3' to 5' direction.

*These A.I. responses have been individually checked to ensure they match the accepted answer, but explanations may still be incorrect. Responses may give guidance but the A.I. might not be able to answer the question! This is particularly the case for questions based on diagrams, which the A.I. typically cannot interpret.
Grade Gorilla uses Gemini, Deepseek and a range of other A.I. chatbots to generate the saved responses. Some answers have had human intervention for clarity or where the A.I. has not been able to answer the question.