Biology Flashcards

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

Answer: Hypotonic

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

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

Answer: Only a specific substrate fits the active site of an enzyme

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

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

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

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

Which base pairs with adenine in a DNA molecule?

Answer: Thymine

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

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

Answer: Photosynthesis

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

A child has blood type O. Which of the following could be the genotypes of the parents?

Answer: IAi and IBi

Blood type O requires genotype ii; both parents must carry at least one i allele, so IAi × IBi can produce ii offspring.

Which part of the nephron is primarily responsible for selective reabsorption of glucose and amino acids?

Answer: Proximal convoluted tubule

The proximal convoluted tubule (PCT) reabsorbs nearly all filtered glucose, amino acids, and a large proportion of water and ions.