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Biology > B.1 Cells Structure and transport > Flashcards

B.1 Cells Structure and transport Flashcards

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1
Q

What is the structure of an animal cell?

A

Animal cells are made up of:

  • nucleus
  • cytoplasm
  • cell membrane
  • mithocondria
  • ribosomes
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2
Q

What is the function of the nucleus?

A

The nucleus contains genetic material, including DNA, which controls the cell’s activities. It is surrounded by the nucleus membrane

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3
Q

What is the function of the Cytoplasm?

A

The Cytoplasm is a jelly-like material that contains dissolved nutrients and salts and structures called organelles. It is where many of the chemical reactions happen.

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4
Q

What is the function of the cell membrane?

A

Its structure is permeable to some substances but not to others. It therefore controls the movement of substances in and out of the cell.

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5
Q

What is the function of the Mithocondria?

A

They are structures in the cytoplasm where aerobic respiration takes place, releasing energy for the cell

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6
Q

What is the function of the ribosomes?

A

Tiny structures where protein synthesis occurs, making all the proteins needed for the cell

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7
Q

What are the additional structures found in plant cells?

A

Cell wall
Chloroplasts
Permanent vacuole

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8
Q

What is the function of the cell wall?

A

Made from cellulose fibres and strengthens the cell and supports the plant

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9
Q

What is the function of the Chloroplasts?

A

Organelles that contains the green pigment, chlorophyll, which absorbs light energy for photosynthesis. Contains the enzymes needed for photosynthesis. They are found in all green parts of a plant. Root cells do not have them as they are under the ground

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10
Q

What is the function of the permanent vacuole?

A

Filled with cell sap to help keep the cell turgid

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11
Q

What are Eukariotic Cells?

A

Cells of animals, plants and fungi are called eukaryotic cells

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12
Q

What are Prokaryotes and what is their structure?

A

A prokaryotic cell consists only of
- cytoplasm and a cell membrane surrounded by a cell wall. The genetic material is not in a nucleus. It forms a single DNA loop. They may contain one ore more extra small rings of DNA called Plasmids. Example are bacteria

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13
Q

What are plasmids?

A

Plasmids are small rings of DNA in Prokaryotic cells. They code for very specific features such as antibiotics resistance

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14
Q

What are flagella?

A

Some bacteria have a flagellum which is a protein strand that moves about and it is used to move about

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15
Q

What are orders of magnitude?

A

They are used to make approx comparisons. They are used to compare cells sizes. You show them using powers of 10

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16
Q

How do you work out orders of magnitude?

A
  • If bigger number / smaller is less than 10 you have same order of magnitude
  • if bigger number / smaller is around 10 you have order of magnitude 10 to the power of 1 or an order of magnitude bigger
  • if bigger number / smaller is around 100 you have order of magnitude 10 to the power of 2 or two order of magnitude bigger
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17
Q

What happens to a cell when it differentiate?

A

It gets subcellular structures which enable it to carry out a particular function

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18
Q

Examples of specialised cells

A

Nerve cells
Muscle cells
Sperm cells

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19
Q

What adaptations do sperm cells have?

A

A large nucleus contains the genetic material for fertilisation The acrosome in the head contains enzymes so that the sperm can penetrate an egg
The middle piece is packed with mitochondria to release energy needed to swim and fertilise the egg
The tail enables the sperm to swim

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20
Q

What are nerve cells and what adaptations do they have?

A

Nerve cells are specialised to carry electrical impulses around the body.
They have:
Dendrites to make connections with other nerve cells
An axon that carries the nerve impulse from one place to the other
Nerve endings or synapses pass impulses to other cells or to muscles using special chemicals. They contain lots of mitochondria

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21
Q

What are muscle cells and what adaptations do they have?

A

They are specialised cells that contract and relax in pairs to move the bones in the body. They are also in the digestive system where they contract so that food is squeezed through the gut.
They have three main adaptations:
- Contain special proteins that slide over each other making the fibres contract
- Contain many mitochondria to transfer the energy needed for the cells to contract and relax
- Can store glycogen, a chemical that can be broken down and used to transfer energy

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22
Q

Adaptations in Root Hair Cells

A
  • The root hair cell has a large surface area to provide contact with soil water.
  • Large permanent vacuole that speeds up the movement of water by osmosis from the soil
  • Many mitochondria that transfer the energy needed for the active transport of mineral ions into the root hair cells
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23
Q

Main adaptations of Photosynthetic cells

A
  • contain specialised green structures called chloroplasts contain chlorophyll needed for photosynthesis
  • they are usually positioned in the leaves and outer layer of the stems to get more light
  • large permanent vacuole that helps keep the cell rigid so that the stem is supported and help leaves spread out to capture light
24
Q

What are the main adaptations of Xylem cells?

A
  • they are alive when first formed but then a special chemical called lignin forms in the cell walls. The cells die and form long hollow tubes that allow water and minerals to move easily from end of the plant to another
25
Q

What are Xylem cells in plants?

A

The Xylem is the transport tissue in plants that carries water and mineral ions from the roots to the highest leaves and shoots
It is also important in supporting the plant

26
Q

What are Phoelm cells?

A

Phoelm is a specialised transport tissue that carries the food made by photosyntesis around the plant. They form tubes like xylem cells but they do not die.

27
Q

What are the adaptations of the Phloem Cells?

A
  • Cell walls between cells breaks down to form sieve plates. These allow water carrying dissolve food to move freely
  • They loose a lot of their internal structures but are supported by companion cells that help keeping them alive. The mitochondria of the companion cells transfer the energy needed to move dissolved food
28
Q

What is Diffusion?

A

Diffusion is the spreading out of particles of a substance from a place where they are in a higher concentration to where they are in a lower concentration down a concentration gradient. It is important to remember that the particles will move in both directions, but there will be a net movement from high to low concentration

29
Q

What factors affect the rate of diffusion?

A
  • Difference in concentration
  • Temperature
  • Available surface area
30
Q

What is a concentration gradient?

A

It is the difference between two areas of concentration. The bigger the difference, the highest the gradient and faster the rate of diffusion

31
Q

How does temperature affect the rate of diffusion?

A

An increase in temperature means the particles move around more quickly

32
Q

Examples of substances that move in and out of cells through diffusion

A
  • simple sugars like glucose
  • gases such as oxygen and carbon dioxide
  • waste products such as urea from the break down of aminoacids in the liver
33
Q

Explain how diffusion happens in respiration

A
  • Oxygen passes from the air in the lungs into the red blood cells. The oxygen moves down a concentration gradient
  • Oxygen also moves from red blood cells to the parts of the body where it is needed
  • Carbon dioxide moves out from the body cells into red blood cells and then into the air in the lungs
34
Q

What type of adaptation is there to make diffusion easier?

A

Increase the surface area of cells membrane so to increase the surface area

35
Q

What is Osmosis?

A

Osmosis is the diffusion of water molecules, from a region where the water molecules are in higher concentration, to a region where they are in lower concentration, through a partially permeable membrane.
(A dilute solution contains a high concentration of water molecules, while a concentrated solution contains a low concentration of water molecules)

36
Q

What molecules are involved in Osmosis

A

Water molecules only

37
Q

What does a dilute solution contain?

A

High water concentration and low sugar (the solute)

38
Q

What does a concentrated solution contain?

A

Low water concentration and high sugar concentration

39
Q

What is a isotonic solution?

A

If the concentration of solutes in the solution outside the cells is the same as the internal concentration

40
Q

What is a Hypertonic solution?

A

If the concentration of solutes in the solution outside the cells is higher thas the internal concentration

41
Q

What is a Hypotonic solution?

A

If the concentration of solutes in the solution outside the cells is lower then the internal concentration

42
Q

How is osmosis used in animal cells?

A

It is used to restore the balance every time the cytoplasm becomes too diluted or too concentrated following chemical reactions

43
Q

What issues can osmosis cause?

A

Cells might swell and burst if too much water moves in. Or if the outside solution becomes much more concentrated water moves out of the cell and the cell shrivels up and dies

44
Q

Why do plants rely on osmosis?

A

Osmosis is important to support their stems and leaves. Water enters into plant cells by osmosis, the vacuole swells, which presses the cytoplasm against the cell wall. The pressure building up is called Turgor. For this to happen fluid around the cell need to be hypotonic

45
Q

What happens to plant cells if the solution around them is hypertonic to the cells content?

A

The cells will become flaccid, the plant will wilt

46
Q

What is active transport?

A

Substances are transported passively down concentration gradients. Often, substances have to be moved from a low to a high concentration - against a concentration gradient.

47
Q

Where does the body get the energy needed for active transport from?

A

Active transport uses energy released during cells respiration.

48
Q

Why do cells that carry out active transport also usually have lots of mitochondria?

A

Because energy is needed

49
Q

Give an example of why active transport is important in plants?

A

For plants to take up mineral ions, ions are moved into root hairs, where they are in a higher concentration than in the dilute solutions in the soil. Active transport then occurs across the root so that the plant takes in the ions it needs from the soil around it

50
Q

Give an example how how Active Transport can be used in animals

A

In animals, glucose molecules have to be moved across the gut wall into the blood. The concentration of glucose in the body is kept steady so sometimes it is lower than the concentration in the gut. When this happens AT is used.

51
Q

How does the surface area to volume ratio vary depending on the size of an organism?

A

The surface area to volume ratio FALLS as an object gets bigger, so simple diffusion is not enough to exchange material between the cells and the environment

52
Q

Why do larger organisms need special systems for exchanging materials with the environment?

A

Because their surface to area ratio is smaller (diffusion distances are longer) so these organisms have special surfaces where exchange takes place which have adapted to be as effective as possible

53
Q

Provide examples of adaptation for exchanging materials

A

The effectiveness of an exchange surface can be increased by:

  • having a large surface area
  • thin membrane to provide a short diffusion path
  • efficient blood supply in animals moves the diffusing substances away from the exchange surfaces and maintain a steep concentration gradient
  • in animals being ventilated makes gas exchange more efficient by maintaining steep concentration gradient
54
Q

Examples of adaptation for transport in humans

A
  • Air is moved in and out of our lungs when we breathe, ventilating the millions of air sacks called alveoli. The alveoli have an enormous surface area and a very rich blood supply for effective gas exchange
  • The villi in the small intestine also have a large surface area, short diffusion paths and rich blood supply
55
Q

Adaptation for materials exchange in plants

A
  • Plant roots have a large surface area made even bigger by the root hair cells
  • Leaves flat and thin, air spaces in the leaves tissues and the presence of the stomata provide a big surface area and maintain a steep gradient

Biology (16 decks)

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