Transport in Cells (1.3) (M) Flashcards

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1
Q

What is diffusion?

A

The spreading out of the particles of any substance in solution, or particles of a gas, resulting in a net movement from an area of higher concentration to an area of lower concentration (across a cell membrane)

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2
Q

2 examples

What are some examples of diffusion?

A
  • oxygen and carbon dioxide in gas exchange
  • the waste product urea from cells into the blood plasma for excretion in the kidney
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3
Q

3 factors needed

What are factors which affect the rate of diffusion?

A
  • the difference in concentrations (concentration gradient)
  • the temperature
  • the surface area of the membrane.
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4
Q

What is the surface area:volume ratio of a single-celled organism like?

A

A single-celled organism has a relatively large surface area to volume ratio.

This allows sufficient transport of molecules into and out of the cell to meet the needs of the organism.

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5
Q

Why is exchanging materials with the environment more difficult in multi-cellular organisms than in single-celled organisms?

What do they have in response to this?

A

due to their smaller surface area:volume ratio

so multi-cellular organisms have specialised organ systems for exchanges and transport systems to carry materials around the body

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6
Q

Why do multicellular organisms have specialised surfaces and organ systems for exchanging materials?

A

to allow sufficient molecules to be transported into and out of cells for the organism’s needs

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7
Q

4 ways

Which factors increase the effectiveness of an exchange surface?

A
  • having a large surface area
  • a membrane that is thin, to provide a short diffusion path
  • (in animals) having an efficient blood supply
  • (in animals, for gaseous exchange) being ventilated.
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8
Q

What is osmosis?

A

Osmosis is the diffusion of water from a dilute solution to a concentrated solution through a partially permeable membrane.

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9
Q

What is active transport?

A

the movement of substances from an area of low concentration to an area of high concentration (against a concentration gradient). This requires energy from respiration.

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10
Q

What is an example of active transport in plants? Why is this useful?

A

Active transport allows the absorption of mineral ions into plant root hairs from very low concentrations in the soil.

Plants require ions for healthy growth.

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11
Q

What is an example of active transport in the body? Why is this useful?

A

It allows sugar molecules to be absorbed from lower concentrations in the gut into the blood which has a higher sugar concentration.

Sugar molecules are used for cell respiration

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12
Q

5 points

How are the small intestines adapted for efficient absorption?

A

Villi (projectiles) provide a large surface area

villi are one cell thick for shorter absorption/diffusion distance

small intestine is very long, increasing time for absorption

good/efficient blood supply to maintain concentration gradient

cells have many mitochondria for energy release for (aerobic) respiration for active transport

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13
Q

4 points

Explain why a species of sea creature may die in water with a low concentration of oxygen

A

concentration gradient less steep

so less oxygen diffuses into the blood

so less (aerobic) respiration occurs so less energy is released

so less metabolism

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14
Q

2 marker

Explain why having only one ventricle makes the circulatory system less efficient than having two ventricles?

A

oxygenated and deoxygenated blood mix

so less oxygen reaches cells

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