Water A1.1.1-1.1.4

What did Charles Darwin suggest about the origin of the first organisms in 1871?

• They appeared in the oceans.

• They appeared in a "warm little pond".

• They appeared in the atmosphere.

• They appeared on land.

Answer explanation

In 1871, Charles Darwin proposed that the first organisms originated in a "warm little pond". This idea suggests a specific environment conducive to the emergence of life, distinguishing it from other options like oceans or land.

Where do most current hypotheses suggest the first cells originated?

• In the atmosphere

• On land

• In the oceans

• In a "warm little pond"

Answer explanation

Most current hypotheses suggest that the first cells originated in the oceans, where conditions were suitable for the formation of organic molecules and early life forms, making it the most widely accepted theory.

What is the significance of water in the formation of the first cells?

• It provided a solid environment for reactions.

• It allowed substances to dissolve and react.

• It was not involved in the formation of cells.

• It acted as a barrier to chemical reactions.

Answer explanation

Water is crucial for the formation of the first cells as it allows substances to dissolve and react, facilitating the necessary chemical processes for life. Without water, these reactions would be limited.

What type of bonds are present between oxygen and hydrogen atoms in a water molecule?

• Ionic bonds

• Non-polar covalent bonds

• Polar covalent bonds

• Metallic bonds

Answer explanation

In a water molecule, the bonds between oxygen and hydrogen atoms are polar covalent bonds. This occurs because oxygen is more electronegative than hydrogen, causing an unequal sharing of electrons and creating a dipole moment.

Why are the covalent bonds in water molecules considered polar?

• Because hydrogen is more attractive to electrons than oxygen.

• Because oxygen is more attractive to electrons than hydrogen.

• Because electrons are shared equally.

• Because they are ionic bonds.

Answer explanation

The covalent bonds in water are polar because oxygen is more electronegative than hydrogen, meaning it attracts electrons more strongly. This creates a partial negative charge on oxygen and a partial positive charge on hydrogen.

What is the result of the unequal sharing of electrons in water molecules?

• The hydrogen atoms have a partial negative charge.

• The oxygen atom has a partial positive charge.

• The hydrogen atoms have a partial positive charge.

• The oxygen atom has a full negative charge.

Answer explanation

In water molecules, oxygen is more electronegative than hydrogen, causing the electrons to be drawn closer to oxygen. This results in hydrogen atoms having a partial positive charge, making the correct answer the third choice.

What is the role of water in the processes of life?

• It prevents molecules from interacting.

• It allows molecules to move and interact.

• It acts as a solid barrier.

• It is not involved in life processes.

Answer explanation

Water is essential for life as it facilitates the movement and interaction of molecules, enabling biochemical reactions necessary for living organisms. Without water, these processes would be severely hindered.

How long has life been evolving since the formation of the first cells?

• Thousands of years

• Millions of years

• Billions of years

• Trillions of years

Answer explanation

Life has been evolving for approximately 3.5 billion years since the first cells appeared. This makes 'billions of years' the correct choice, as the other options underestimate the vast timescale of evolution.

What is the primary state of water that supports life processes?

• Solid

• Liquid

• Gas

• Plasma

Answer explanation

The primary state of water that supports life processes is liquid. It is essential for biochemical reactions, nutrient transport, and temperature regulation in living organisms.

Which of the following is NOT a characteristic of water molecules?

• They have polar covalent bonds.

• They allow chemical reactions to occur.

• They are non-polar.

• They have partial charges.

Answer explanation

Water molecules are polar due to their polar covalent bonds and partial charges, allowing them to participate in chemical reactions. Therefore, the statement that they are non-polar is NOT a characteristic of water molecules.