water and transport Flashcards
Why is water vital to living organisms?
Water acts as a solvent, dissolving substances necessary for biological reactions, which typically occur in solution.
Water transports substances
What is the structure of a water molecule?
- A water molecule (H₂O) consists of one oxygen atom covalently bonded to two hydrogen atoms.
- The shared electrons are pulled towards the oxygen, leaving the hydrogen atoms slightly positive (δ⁺) and the oxygen slightly negative (δ⁻).
- This creates a dipolar molecule with a partial negative charge on one side and a partial positive charge on the other.
What is hydrogen bonding in water?
Hydrogen bonds form between the δ⁻ oxygen of one water molecule and the δ⁺ hydrogen of another.
These weak bonds collectively give water unique properties, such as cohesion and its ability to act as a solvent.
How does water’s dipole nature aid in transporting substances?
- The dipole nature of water makes it cohesive and a good solvent.
- Cohesion helps water flow, which is essential for transporting substances in biological systems.
- As a solvent, water dissolves ionic and polar substances, enabling their transport in solution.
Why is water cohesive, and why is this important?
Cohesion is the attraction between water molecules due to hydrogen bonding.
It enables water to flow and facilitates the transport of substances like nutrients and gases.
How does water act as a good solvent?
Water dissolves ionic substances (e.g., salts) by surrounding the positive and negative ions, preventing them from clumping together.
How does water facilitate metabolic reactions?
As a solvent, water dissolves reactants, allowing chemical reactions to occur efficiently.
Dissolved metabolites are more chemically reactive and can be transported easily.
Why is water described as a dipolar molecule?
A water molecule has a partial negative charge (δ⁻) on the oxygen atom and partial positive charges (δ⁺) on the hydrogen atoms due to the uneven sharing of electrons.
This makes water dipolar with distinct charges on either end.
What are hydrogen bonds, and why are they important in water?
Hydrogen bonds form between the δ⁺ hydrogen of one water molecule and the δ⁻ oxygen of another.
These bonds give water its unique properties, such as cohesion, adhesion, and its role as a solvent.
How does water dissolve ionic substances like salt?
The positive ends of water molecules are attracted to negative ions, while the negative ends are attracted to positive ions.
This causes the ions to become surrounded by water molecules and dissolve.
What makes water a good solvent?
Water’s dipolar nature allows it to dissolve many substances, including ionic compounds and polar molecules.
This is essential for biological processes where substances need to be transported or react in solution.
Why do multicellular organisms need mass transport systems?
In small organisms, diffusion alone is sufficient because of the short distances substances need to travel.
In larger organisms, diffusion is too slow over long distances, so transport systems like the circulatory system are required to move nutrients, gases, and waste efficiently.
What is the role of water in mass transport systems in mammals?
Water is the medium for transporting dissolved substances like oxygen, glucose, and ions in blood.
It ensures nutrients reach cells and waste products are removed efficiently.
Why is diffusion insufficient for large multicellular organisms?
In large organisms, the distances substances need to travel are too great for diffusion to be efficient.
Specialized transport systems (e.g., circulatory systems) are required to move substances quickly and efficiently.
How does the dipole nature of water help it dissolve polar substances?
The δ⁺ hydrogen atoms are attracted to negatively charged particles, while the δ⁻ oxygen atoms are attracted to positively charged particles.
This allows water to surround and dissolve polar substances effectively.
