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Biology Unit 3 > Transport in Organisms > Flashcards

Transport in Organisms Flashcards

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1
Q

What is osmosis?

A

A type of diffusion in which water moves across a partially permeable membrane

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2
Q

What is a partially permeable membrane?

A

Membranes which only allow certain particles through them

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3
Q

What is the cytoplasm made up of?

A

Chemicals dissolved in water. It contains concentrated solutions of salts and sugars

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4
Q

Water moves from an area of…

A

… high concentration of water molecules to an area of low concentration of water molecules down a concentration gradient across the cell membrane

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5
Q

Why must the concentration of water molecules inside your cells stay the same?

A

So they still work properly. Osmosis is important because sometimes conditions outside the cells can be very different.

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6
Q

Why might the cytoplasm because too concentrated?

A

The cell may use up too much water in its chemical reactions. More water is immediately moved into the cytoplasm, which becomes too dilute because cells also make water in chemical reactions. Osmosis happens again.

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7
Q

If the solution outside a cell becomes more dilute that in the cytoplasm…

A

Water molecules will move into the cell and it could swell and burst

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8
Q

What do plants rely on osmosis for?

A

To support their stems and roots

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9
Q

How does water support the stem?

A

It moves into cells, causing the vacuole to swell and press the cytoplasm against the cell wall. Pressure builds up until no more water can enter and the cell is hard and rigid.

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10
Q

What do plants need to maintain strong stems?

A

The fluid around cells to have a higher concentration of water to keep osmosis going in the right directions so plant tissues can be supported.

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11
Q

What is active transport?

A

The movement of dissolved substances from an area of low concentration to an area of high concentration against the concentration gradient

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12
Q

What does active transport enable cells to do?

A

Absorb substances from very dilute solutions

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13
Q

Describe the process of active transport.

A

A transport protein lies just outside of the cell membrane. This picks up a molecule, then rotates and releases it inside the cell, which requires energy. It then rotates back to its original position, requiring more energy.

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14
Q

What do cells need in order to carry out successful active transport?

A

Lots of mitochondria e.g. root hair cells

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15
Q

Name two examples of active transport.

A
  • Absorption of mineral ions from soil by plant cells

* Absorption of glucose out of your gut and kidney tubules

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16
Q

Why do you use up glucose when you exercise?

A

You break it down to release energy used to make your muscles contract

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17
Q

How do you release water and mineral ions?

A

Sweat and urine

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18
Q

Why is it important to drink water whilst exercising?

A

Water will leave your cells by osmosis and become dehydrated so they won’t work as efficiently

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19
Q

Isotonic drinks claim to…

A

Contain more electrolytes (mineral ions) than other drinks as well as lots of glucose and water

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20
Q

What do scientists think?

A

Sports drinks are not needed for activities lasting less than an hour

21
Q

What is the advantage of drinking milk instead of a sports drink?

A

It contains the same amount of energy as well as extra protein and vitamins

22
Q

What can you add to orange juice to ensure it efficiently replaced lost water, mineral ions and glucose?

A

Add a pinch of salt

23
Q

Why is it difficult for substances to get to every cell by diffusion in large organisms?

A

Because the SA:V ratio gets smaller so transport becomes more difficult

24
Q

What are many special surfaces in organisms adapted for?

A

Gas and solute exchange

25
Q

The effectiveness of an exchange surface can be increased by:

A
  • Large SA
  • Short diffusion path
  • Good blood supply to maintain steep concentration gradient
  • Good ventilation to maintain the concentration gradient
26
Q

How are the lungs adapted for exchange?

A
  • Made up of clusters of alveoli (tiny air sacs). The spherical shape gives them a large SA
  • Oxygen moves out of the lungs and into the blood, CO2 moves out of the blood and into the lungs
  • Layer of cells between air in the lungs and blood in the capillaries is very thin so diffusion takes place over a short distance
  • Good ventilation
27
Q

If the solution inside the cytoplasm becomes more dilute than the outside solution…

A

Water will move out of cells and they may shrink and shrivel. This is why it is important to maintain good internal conditions.

28
Q

What is breathing?

A

A form of ventilation that takes place in the breathing system

29
Q

Lungs are found in the thorax, protected by ribcage. They are segregated from digestive organs in the abdomen by the diaphragm (strong sheet of muscle).

A

Yes.

30
Q

How do we breathe?

A
  1. The intercostal muscles make the ribs move up and out and the diaphragm contracts flattens from its usual domed shape, increasing the volume of the thorax and decreasing the pressure
  2. Atmospheric air at a higher pressure than the air inside the thorax moves into the lungs
  3. The intercostal muscles relax and ribs fall and the diaphragm moves up. The means the volume of the chest gets smaller and the pressure rises
  4. The pressure of the air inside the lungs is higher than that in the atmosphere so air is forced out
31
Q

Breathing helps to encourage diffusion because when you breath in, oxygen rich blood is transported into the lungs so continually diffuses into the bloodstream by alveoli. CO2 can also continually move out of the bloodstream and into the lungs.

A

Yes.

32
Q

Why may people struggle to breathe?

A
  • Tubes leading up to the lungs might be very narrow so less air gets through
  • Te structure of the alveoli break down leaving a smaller area of gas exchange
  • They may be paralysed in an accident
33
Q

What disease is the iron lung used to treat one of the effects of?

A

Polio

34
Q

How does the iron lung work?

A
  • Patient lies in metal cylinder with a tight seal around the neck
  • Air is pumped out of the vacuum so the chest wall moves up to crease an increased volume and decreased pressure in the thorax, so atmospheric air moves in
  • The vacuum is switched off automatically and the ribs move down, increasing pressure in the thorax so air is moved out if the lungs
35
Q

What is the more modern version of the iron lung called that fits just around the chest?

A

The shell

36
Q

How does positive pressure breathing work?

A
  • A carefully measured breath of air is forced into the patient’s lungs under positive pressure
  • The lungs inflate and the air pressure stops
  • The lungs begin to deflate and let air out so the ribs move down
37
Q

What are some advantages of positive pressure breathing aids?

A
  • Some can help with major operations and surgery
  • Modern systems link to a computer so patients have some control over their breathing

However, the tube down the tranches can be uncomfortable

38
Q

In the digestive system, digested molecules move into the bloodstream by a combination of diffusion and active transport

A

The molecules are small enough to pass through the walls of the small intestine and into the gut. They move down a steep concentration gradient because there are lots of good molecules in the gut and a lower concentration of in the blood.

39
Q

How is the digestive system adapted to maintain efficient exchange of materials?

A
  • The lining of the SI has lots of villi which increases the SA for diffusion so we can absorb enough digested food molecules to survive
  • Each villus is covered in micro villi to increase SA for diffusion
  • The lining of the good has a good blood supply to carry away molecules as soon as they have diffused from one side to another too allow for a steep concentration gradient and rapid diffusion
40
Q

Why must glucose and other dissolved molecules be moved by active transport?

A

As the time since you are gets longer, you have more food molecules in your blood than your small intestine but these molecules are moved by active transport to ensure no digested food is wasted and lost in faeces

41
Q

How do plants take up water, CO2 and mineral ions?

A
  • Water = osmosis
  • CO2 = diffusion through the leaves
  • Mineral ions = active transport
42
Q

How is diffusion of CO2 made efficient?

A
  • Leaves have a flat shape so a large SA and a short distance over which diffusion takes place
  • There are lots of air spaces to allow CO2 to come into contact with lots of cells
43
Q

Why do plants lose water?

A

Leaf cells always lose water by evaporation because stomata are open

44
Q

How are plants adapted to lose as little water as possible?

A
  • Leaves only allow CO2 in when it is needed
  • They have a waterproof and has proof layer called the waxy cuticle
  • Stomata are opened and closed by guard cells
  • CO2 diffuses through the air spaces and O2 diffuses out to maintain a steep concentration gradient
45
Q

How are roots adapted to take in lots of water?

A
  • Roots are thin with a large SA and their cells have tiny projections which push out between soil particles
  • Water moves into the cells by osmosis across a partially permeable membrane and only has a short distance to the xylem where it is moved up the stem
  • Root hair cells have lots of mitochondria to allow the active transport of mineral ions
46
Q

What is evaporation?

A

Loss of water vapour

47
Q

Why does transpiration occur?

A

As water evaporates from the surface of the leaves, more water is pulled up through the xylem to take it’s place

48
Q

Anything that affects the rate of photosynthesis will affect the rate of evaporation. Hot, dry and windy conditions affect evaporation.

A

Yes.

49
Q

How do plants deal with transpiration?

A
  • Most stomata are found on the underside of leaves so they are not in direct sunlight to reduce the time they’re open
  • Leaves will collapse and wilt to a minimum surface area for water loss and close their stomata so no photosynthesis can occur and the plant will overheat

Biology Unit 3 (3 decks)

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