Front

What is a hydrogen bond?

Back

Bond between hydrogen and an electronegative atom

Answer explanation

A hydrogen bond is specifically a weak attraction between a hydrogen atom and an electronegative atom, such as oxygen or nitrogen. This distinguishes it from bonds between hydrogen atoms or electronegative atoms alone.

Front

How many hydrogen bonds can one water molecule form?

Back

Four

Answer explanation

A water molecule can form four hydrogen bonds due to its two hydrogen atoms and two lone pairs of electrons on the oxygen atom. This allows for a tetrahedral arrangement, maximizing hydrogen bonding.

Front

What bonds connect nitrogen bases in DNA?

Back

Hydrogen bonds

Answer explanation

Hydrogen bonds are the weak interactions that hold the nitrogenous bases together in DNA, allowing for the double helix structure. These bonds form between complementary bases, such as adenine and thymine, or guanine and cytosine.

Front

How many hydrogen bonds form between cytosine and guanine in DNA?

Back

Three

Answer explanation

Cytosine and guanine form three hydrogen bonds in DNA, which is more than the two bonds formed between adenine and thymine. This triple bonding contributes to the stability of the DNA double helix.

Front

Which property of water helps it move from roots to leaves in plants?

Back

Capillary action

Answer explanation

Capillary action is the property of water that allows it to move through narrow spaces, such as the xylem in plants, from roots to leaves. This movement is due to the combination of cohesion and adhesion, but capillary action is the key process.

Front

Why are coastal areas cooler?

Back

Because water has a high specific heat

Answer explanation

Coastal regions are cooler due to the high specific heat of water, which allows it to absorb and store heat without significant temperature changes. This moderates the climate, keeping coastal areas cooler than inland regions.

Front

What happens to water's density when it freezes?

Back

It decreases

Answer explanation

The density of water decreases upon freezing because ice expands and occupies more volume than liquid water. This is why ice floats on water.

Front

What do hydrogen bonds do in DNA?

Back

Stabilize the double helix

Answer explanation

Hydrogen bonds between complementary base pairs stabilize the double helix structure of DNA, ensuring its integrity and proper functioning during processes like replication and transcription.

Front

Which nitrogen bases pair together in DNA?

Back

Adenine with Thymine, and Cytosine with Guanine

Front

What property of water allows insects to walk on its surface?

Back

Surface tension