EmSAT Biology 5

Question 1

A red blood cell is placed in a solution and it swells and bursts. What type of solution was it placed in?

Accepted Answer

Hypotonic

Answer

In a hypotonic solution (lower solute concentration than the cell), water enters the cell by osmosis causing it to swell and lyse.

Question 2

Which of the following correctly describes the lock-and-key model of enzyme action?

Accepted Answer

Only a specific substrate fits the active site of an enzyme

Answer

The lock-and-key model proposes that only a substrate with a complementary shape can bind to the enzyme's specific active site.

Question 3

What is the role of the sinoatrial (SA) node in the human heart?

Accepted Answer

It acts as the heart's natural pacemaker initiating electrical impulses

Answer

The SA node generates electrical impulses that spread across the atria, initiating each heartbeat and setting the heart rate.

Question 4

Which base pairs with adenine in a DNA molecule?

Accepted Answer

Thymine

Answer

In DNA, adenine (A) pairs with thymine (T) via two hydrogen bonds, following Chargaff's base-pairing rules.

Question 5

Which process converts light energy into chemical energy stored in glucose?

Accepted Answer

Photosynthesis

Answer

Photosynthesis occurs in chloroplasts and uses light energy to convert CO₂ and H₂O into glucose and O₂.

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