B2.1 Supplying the Cell - Diffusion, Osmosis, Active Transport Flashcards

Diffusion, Osmosis, Active Transport

1
Q

What is diffusion?

A

The passive net overall movement of particles from a region of high concentration to a region of low concentration down the concentration gradient.

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2
Q

Particles move โ€ฆโ€ฆ. and โ€ฆโ€ฆ.. by diffusion.

A

Particles move constantly and randomly by diffusion

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3
Q

What key gases do we need to diffuse from our lungs to our blood stream?

A

Oxygen

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4
Q

What key nutrient do we need to diffuse from our blood stream to our muscle cells?

A

Glucose

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5
Q

What factors affect diffusion?

A

Surface area

Temperature

Concentration gradient

Distance

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6
Q

Name key adaptations of the body to facillitate diffusion?

A

Alveoli

  • They are very thin - small distance to diffuse over
  • They are covered by a network of fine capillaries - diffuse straight into bloodstream, maintains concentration gradient
  • They are moist
  • They have a large combined surface area.

Small intestines

  • Villi & Microvilli - increases surface area, therefore volume that can be absorbed
  • Good blood supply โ€“ substances diffuse straight into the bloodstream, maintains concentration gradient
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7
Q

What role does diffusion play in nerve impulses?

A
  • Diffusion allows a nerve impulse to travel between two neurones at a synapse
  • Neurotransmitter molecules diffuse from vesicles towards the neurotransmitter receptors, moving from an area of high concentration to low concentration.
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8
Q

How the is placental organ is adapted to maximise diffusion?

A
  • A large surface area between it and the uterus wall.
  • Villi (finger like projections that extend into the uterus wall), which further increase the surface area of the placenta.
  • A rich supply of maternal blood vessels.
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9
Q

What role does diffusion play in enabling photosynthesis?

A
  • Carbon dioxide diffuses in through the stomata.
  • Oxygen and water diffuse out of the stomata
  • During photosynthesis, the level of CO2 is low inside the leaf, creating a big concentration gradient so CO2 diffuses into the cell
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10
Q

Define osmosis.

A

Osmosis is a special type of diffusion. The diffusion of water molecules across a partially (selectively) permeable membrane from an area of high water potential to an area of lower water potential (down a water potential gradient).

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11
Q

What is meant by โ€˜hypertonicโ€™?

A

A fluid has a higher osmotic pressure (lower water potential) than a particular fluid, typically a body fluid or intracellular fluid.

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12
Q

What is meant by the term โ€˜hypotonicโ€™?

A

A fluid has a lower osmotic pressure (higher water potential) than a particular fluid, typically a body fluid or intracellular fluid.

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13
Q

Why is osmosis important to plant cells in particular?

A

The vacuole which helps mantain the cells structure is filled by osmosis.

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14
Q

Explain the term โ€˜turgidโ€™.

A

When water enters the cell by osmosis and fills the vacuole. This pushes against the cell wall, making the cell turgid.

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15
Q

Explain the term โ€˜flaccidโ€™.

A

When water moves out of the cell by osmosis, the vacuole shrinks and the cell becomes flaccid

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16
Q

This happens if too much water leaves a plant cell, and the cytoplasm moves away from the cell wall.

A

Plasmolysis

17
Q

What is an isotonic solution?

A

An isotonic solution is one that has the same osmolarity, or solute concentration, as another solution.

18
Q

What is โ€˜lysisโ€™?

A

When an animal cell is placed in a hypotonic solution causing too much water to enter the cell by osmosis and the cell to swell and burst.

19
Q

What is โ€˜crenationโ€™?

A

When an animal cell is placed in a hypertonic solution causing too much water to leave the cell by osmosis and the cell to shrink and shrivel.

20
Q

Osmosis takes place over aโ€ฆ

A

Selectively/semi-permeable membrane

21
Q

Define active transport.

A

The transport of particles from an area of low concentration to an area of high concentration, against a concentration gradient using ATP (energy).

22
Q

What are carrier proteins?

A
  • Protiens embembedded within the cell surface membrane.
  • They bind with useful molecules and then use ATP to rotate or change shape to transport the molecule into the cell.
  • Allow the transport of useful molecules against a concentration gratient
23
Q

State an example of active transport in plants.

A

Root hair cells - Transport of mineral ions from low concentration in the soil to higher concentration in the root hair cell.

24
Q

State two examples of active transport in animals.

A
  1. Nerve cells - active transport used to pump sodium & potassium ions required to create nerve impulses
  2. Digestion - active transport used to transport the final products of digestion into the bloodstream through the villi
25
Q

Why do cells that carry out active transport contain a lot of mitochondria?

A

Mitochondira produce energy and energy is required for active transport to take place.

26
Q

What are the adaptations of the alveoli?

A