10 Questions
Where is it thought that life began?
The ocean
What is the shape of a water molecule?
Bent
What is the force that forms between two water molecules?
Hydrogen bond
Why are water molecules able to move around and interact?
Because they are in a liquid state
Why do positively charged particles and negatively charged particles attract each other?
Because they have opposite charges
What is the main reason why water can be transported under tension in plants?
Cohesion between water molecules due to hydrogen bonds
What would happen to the column of water in a xylem vessel if many hydrogen bonds were broken simultaneously?
The column of water would break
Why do objects, such as steel pins, float on the surface of water despite being denser?
Because of the surface tension of water
What is the result of attractions between water molecules and the cell walls of leaf cells?
Tension in the leaves develops
Why is surface tension stronger in water than in most other liquids?
Because of strong hydrogen bonding between water molecules
Study Notes
Origins of Life
- Charles Darwin proposed that life began in a "warm little pond"
- Today, most hypotheses suggest that life began in the oceans
- The first cells formed when a small volume of water became enclosed in a membrane
- Substances dissolved in the water allowed for chemical reactions to occur between solutes
Properties of Water
- Water molecules have polar covalent bonds due to unequal sharing of electrons between oxygen and hydrogen atoms
- This creates a partial positive charge on hydrogen atoms and a partial negative charge on the oxygen atom
- Water molecules are bent, forming a polar molecule with two poles
Hydrogen Bonds
- Hydrogen bonds are weak intermolecular forces between water molecules
- Formed when a slightly positive hydrogen atom is attracted to a slightly negative atom of another polar molecule
- Although weak, hydrogen bonds are numerous and collectively give water its unique properties
Importance of Hydrogen Bonds in Living Organisms
- Cohesion allows for the transport of water under tension in plants
- Hydrogen bonds make water cohesive, enabling it to withstand tension in xylem vessels
- Surface tension, caused by hydrogen bonding, allows for objects to float on the surface of water
This quiz explores the origins of life on Earth, from the first cells to the evolution of life forms. Discover how water played a crucial role in the emergence of life.
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