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SCIENCE-BIOLOGY GCSE > Chapter 1 - Cell Biology > Flashcards

Chapter 1 - Cell Biology Flashcards

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1
Q

What are the two different type of cells?

A

Prokaryotic or eukaryotic

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2
Q

What are eukaryotic cells?

A

Animal and plant cells

They are more complex

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3
Q

What are prokaryotic cells?

A

Smaller and simpler

Eg bacteria

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4
Q

What sub-cellular structures does an animal cell contain?

A 
Nucleus
Cytoplasm
Cell membrane
Mitochondria
Ribosomes
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5
Q

What does the nucleus do?

A

Contains genetic material that controls the activities of the cell

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6
Q

What does the cytoplasm do?

A

Its a gel like substance where most of the chemical reactions happen.
It contains enzymes that control these chemical reactions

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7
Q

What does the cell membrane do?

A

Holds the cell together and controls what goes in and out

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8
Q

What does mitochondria do?

A

These are where most of the reactions for aerobic respiration take place.

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9
Q

What do ribosomes do?

A

These are where proteins are made in the cell

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10
Q

What sub-cellular organisms do plant cells contain?

A

Everything an animal cell contains (nucleus, mitochondria, ribosomes, cell membrane, cytoplasm) plus a few extra:

  • cell wall
  • Permanent vacuole
  • Chloroplasts
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11
Q

What does the cell wall do?

A

It supports the cell and strengthens it.

Its made of cellulose.

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12
Q

What does the vacuole do?

A

Contains cell sap which is a weak solution of sugar and salts
Vacuoles might store food or any variety of nutrients a cell might need to survive. They can even store waste products so the rest of the cell is protected from contamin

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13
Q

What do chloroplasts do?

A

This is where photosynthesis occurs.

Chloroplasts contain a green substance called CHLOROPHYLL which absorbs light needed for photosynthesis

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14
Q

What sub-cellular structures does a bacteria cell contain?

A
  • Cytoplasm
  • cell membrane
  • cell wall
  • plasmids
  • single circular strand of DNA
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15
Q

What are plasmids?

A

Small rings of DNA

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16
Q

What are light microscopes? What do we use them for?

A

They use lights and lenses.

They let us see individual cells and large sub-cellular structures such as nuclei

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17
Q

What are electron microscopes and what do we use them for?

A

They use electrons instead of light to form an image
They have a higher magnification than a light microscope.
They let us see things such as the internal structures of mitochondria and chloroplasts and also ribosomes and plasmids.

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18
Q

What is the formula for magnification?

A

Magnification=image size/actual size

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19
Q

What is differentiation? When does it normally occur?

A

The process by which a cell changes to become specialised for its job.
It normally occurs as an organism develops

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20
Q

What are some examples of specialised cells?

A 
Sperm cells
Nerve cells
Muscle cells
Root hair cells
Xylem and phloem
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21
Q

How are sperm cells specialised for reproduction?

A
  • long tail to help it swim
  • streamlined head to help it swim
  • lots of mitochondria to provide the energy needed
  • carries enzymes in its head to digest through the egg cell membrane.
22
Q

How are nerve cells specialised for rapid signalling?

A
  • the cells are long (to cover more distance)

- branched connections at their ends to connect to other nerve cells and form a network throughout the body

23
Q

How are muscle cells specialised for contraction?

A
  • long cells so they have space to contract

- lots if mitochondria to generate the energy needed for contraction

24
Q

How are root hair cells specialised for absorbing water and minerals?

A
  • The “hairs” give the plant a larger surface area for absorbing water and mineral ions from the soil
25
Q

How are xylem and phloem cells specialised for transporting substances?

A

Xylem cells
- hollow in centre so stuff can flow through
Phloem
- few sub-cellular structures so stuff can flow through

26
Q

What are chromosomes

A

Coiled up lengths of DNA molecules.
Each chromosome carries a large number of genes which control different characteristics.
Body cells normally have two copies of each chromosome - one from the mother and one from the father.

27
Q

What is mitosis? Why is it used?

A

The stage of the cell cycle where the cell divides.

It is used to grow and replace cells that have been damaged

28
Q

What are the two main stages of the cell cycle?

A

Growth and DNA Replication

Mitosis

29
Q

What happens during the Growth And DNA Replication phase?

A

The cell has to grow and increase the number of sub-cellular structures such as mitochondria and ribosomes.
It then duplicates its DNA so theres a copy for the new cell. The DNA is copied and forms x-shaped chromosomes. Each arm of the chromosome is the exact same as the other.

30
Q

What happens during the Mitosis phase?

A

The chromosomes line up at the centre of the cell and the cell fibres pull them apart. The two arms of each chromosome go to opposite ends of the cell.
Membranes form around each set of chromosomes. These become the nuclei of the new cells.
The cell membrane and cytoplasm then divide.

31
Q

What are stem cells?

A

Stem cells are undifferentiated cells

32
Q

Where are stem cells found? What do they have potential to do?

A

Early human embryos. They have the potential to turn into any type of cell.
They are also found in bone marrow. However these cannot turn into any type of cell

33
Q

How are stem cells used as medicine?

A

Stem cells transferred from the bone marrow of a healthy person can replace faulty blood cells in the patient who receives them.
Embryonic stem cells could possibly be used to replace faulty cells in sick people. You could make: nerve cells for people paralysed by spinal injuries, insulin producing cells for diabetes etc

34
Q

What is therapeutic cloning?

A

Its when the cells from an embryo could be made to have the same genetic information as the patient. This means that it wouldn’t be rejected by the patient

35
Q

What are the risks with stem cells in medicine?

A

The stem cells may become contaminated with a virus which could be passed on to the patient and make them sicker.

36
Q

What are the arguments for and against stem cell research?

A
  • they feel that human embryos shouldn’t be used for experiments as it is a potential human life.
  • Some believe that curing existing patients is more important than curing existing patients
  • embryos used are normally those from fertility clinics and if they are not used then they are normally thrown away
37
Q

Where are stem cells found in plants?

A

In the meristems

38
Q

Why would someone want to clone a plant?

A

To prevent extinction of a rara species

To grown identical crops with desired features such as disease resistance

39
Q

What is diffusion?

A

Diffusion is the spreading out of particles from an area of HIGHER concentration to an area of LOWER concentration

40
Q

Where does diffusion happen?

A

In both solutions and gases

Eg perfume being sprayed in the air

41
Q

What affects the rate of diffusion?

A

A higher temperature means particles have more energy so move around faster
The larger the concentration gradient the faster the diffusion rate
The larger the surface area of the membrane the faster the diffusion rate as more particles can pass through at once.

42
Q

How do cell membranes function during diffusion?

A

they hold the cell together but they allow stuff in and out as well.
Only small molecules such as oxygen, glucose, amino acids and water can pass through cell membranes

43
Q

What is osmosis?

A

Osmosis is the movement of water molecules across a partially permeable membrane from a region of HIGHER water concentration to a region of lower water concentration

44
Q

What is a partially permeable membrane?

A

A membrane with very small holes to allow water to pass through

45
Q

What is active transport?

A

When a substance is absorbed against a concentration gradient

46
Q

What is an example of a cell that uses active transport

A

A root hair cell
They need mineral ions from the soil which the concentration is normally greater inside the cell than outside

It is also used in the gut when there is a lower concentration of nutrients in the gut but a higher concentration of nutrients in the blood.

47
Q

How do you work out the surface area to volume ratio?

A

Find the volume (l x w x h)
Find the surface area

Then put them in a ratio of surface area to volume
Eg 64:32
This would then cancel down to 2:1

The larger the SA/V ratio is the, the more efficient it is

48
Q

How are exchange surfaces adapted fir efficient diffusion?

A
  • thin membrane so there is only a short distance to diffuse
  • large surface area so lots of a substance can diffuse at once
  • in animals, they have lots of blood vessels to get stuff into and out of the blood quickly.
49
Q

How are the alveoli adapted for gas exchange?

A

They have an enormous surface area
A moist lining for dissolving gases
Very thin walls
A good blood supply

50
Q

How are the villi adapted for digestion?

A

They increase the surface area in a big way so that digested food is absorbed much more quickly in the blood
A single layer of surface cells
A good blood supply and quick absorption

51
Q

How do the structure of leaves let gases diffuse in and out if cells?

A

1) carbon dioxide diffuses into the air spaces within the leaf. Then it diffuses into the cells where photosynthesis happens. The leafs structure is adapted so that this can happen easily.
2) the underneath of the leaf is an exchange surface. It is covered with stomata which allows the carbon dioxide through.
3) oxygen and water vapour also diffuse out of the stomata
4) guard cells control the size of the stomata. They close the stomata if the plant is losing water faster than it is gaining it.
5) the flattened shape of the leaf increases the area of this exchange surface so that it is more efficient

SCIENCE-BIOLOGY GCSE (7 decks)

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