Further additional science (up to November 2016)


What is osmosis?
The diffusion of water particles from a dilute to a more concentrated solution through a partially permeable membrane

What is active transport?
The movement of particles against a concentration gradient. Requires a protein carrier molecule and energy from respiration (ATP)

When are exchange surfaces most efficient?

  • Have a large surface area • Are thin (short diffusion path) • Have a good/efficient blood supply (animals) • Are ventilated (animals)

What do the alveoli have to make them more efficient?
They have an excellent blood supply (capillaries) a large surface area and the walls are thin (short diffusion path)

What's an example of where active transport is needed in plants?
Mineral ions are more abundant inside the root hair cells but because there are small quantities in the soil, the root hair cell needs to move them against the concentration gradient and into the cell.

What's are arguments for sports drinks?
Water doesn't have adequate sodium and carbohydrates. Water doesn't have the performance benefits of a sports drink. Water doesn't have flavour to drive the desire to drink

What are arguments against sports drinks?
Only work for endurance athletes not just people who like to keep fit or teenagers. There's a lot of bias in the industry. Science behind them is poorly conducted (e.g small sample sizes)

Why are sports drinks consumed?
During exercise blood sugar (glucose) is required for respiration because muscles need oxygen to work. Althletes also loose water via sweat, as well as ions such as Na+ and K+ (Electrolytes)

What is the transpiration stream?
Roots to xylem to the leaves and then evaporates through transpiration

What is a transportation system in a plant for water & minerals?
Water & minerals are needed throughout the plant, so the transpiration stream moves them from the roots via xylem into the leaves. Most of the water is used in photosynthesis but some is lost through evaporation (transpiration).

What is the transportation system in a plant for Dissolved sugars?
Dissolved sugars are transported via the phloem tissue to growing regions or storage.

What conditions would increase water loss from a plant?
Hot, dry and/or windy conditions because they all cause more evaporation. Heat gives the particles more energy to escape the forces of attraction and low humidity causes more diffusion because of the higher concentration gradient.

What is the role of the stomata in the leaf?
To control water loss, allow carbon dioxide inside the leaf for photosynthesis and allow oxygen, the waste product of photosynthesis out.

What happens when we inhale?
There is a higher/ increased air volume inside the lungs and a lower air pressure outside so air is drawn in. The intercostal muscles contract, the ribs move up & out and the diaphragm flattens (contracts)

What happens when we exhale?
The intercostal muscles relax. There is a lower/ decreased volume, a higher pressure inside the lungs and lower out so air is pushed out. The diaphragm relaxes.

What's a negative pressure system and how does it…


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