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GCSE Combined Science: Biology (Higher) > Topic 1 > Flashcards

Topic 1 Flashcards

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1
Q

Prokaryotic Cells

A

It’s a single-celled organism… Bacteria are an example of prokaryotes. Prokaryotic cells do not contain a nucleus or any other membrane-bound organelle. Prokaryotes include two groups: bacteria and another group called archaea.

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2
Q

Eukaryotic cells

A

Your cells are eukaryotic. Eukaryotic cells contain membrane-bound organelles, including a nucleus. Eukaryotes can be single-celled or multi-celled, such as you, me, plants, fungi, and insects.

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3
Q

What is the role of the ribosome?

A

Where proteins are made in the cell

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4
Q

What happens in the nucleus?

A

contains genetic material that controls the activities of the cell.

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5
Q

What happens in the cytoplasm?

A

Gel-like substance where chemical reactions happen.

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6
Q

Name and describe the structure of an animal cell

A
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7
Q

What is the cell wall made up of, and what does it do?

A

Cellulose: strong

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8
Q

Where does photosynthesis occur?

A

Chloroplasts

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9
Q

What does a permanent vacuole contain?

A

Cell sap

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10
Q

Name and describe the structure of a plant cell…

A
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11
Q

Bacterial Cell

(include: what type of cell it is, etc)

A
  • Prokaryotic cell
  • Don’t have a nucleus
    • Single cellular strand of DNA float freely in cytoplasm
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12
Q

Magnification = …

A

size of image ÷ size of real object

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13
Q

What is a nanometre in standard form?

A

1 x 10-9

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14
Q

What does resolving power mean?

A

A measure of the ability to distinguish between two separate points that are very close together.

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15
Q

What is the difference between a light microscope and an Electron Microscope?

A

Electron Microscope:

  1. x 2,000,000
  2. Invented in the 1930s
  3. Can see the subcellular structures inside cells
  4. Use a beam of electrons to form an image
  5. resolving power - 200nm
  6. Very large, expensive and have to be kept in special temperature, pressure and humidity

Light Microscope:

  1. x 2000
  2. Invented in the mid-17th Century
  3. To look at cells
  4. It uses beams of light to form an image of an object
  5. resolving power - 0.2nm
  6. See image below
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16
Q

Label an animal cell… Give definitions…

A
  • Nucleus - controls all the activities of the cell and is surrounded by the nuclear membrane. Contains the genes on the chromosomes that carry the instructions for making the proteins needed to build new cells or new organisms.
  • Cytoplasm - A liquid gel in which the organelles are suspended and where most of the chemical reactions needed for life take place
  • Cell Membrane - Controls the passage of substances such as glucose and mineral ions into the cell. It also controls the movement of substances such as urea.
  • Mitochondria - Structures in the cytoplasm where aerobic respiration takes place, releasing energy for the cell.
  • Ribosomes - Where protein synthesis takes place, making all the proteins needed in the cell
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17
Q

Label a Plant cell… Give definitions…

A
  • Cell Wall - the rigid structure around the contents of a cell that controls what moves in and out of the cell
  • Cellulose - The complex carbohydrate that makes up plant and algal cell walls and gives them strength
  • Chloroplasts - The organelles in which photosynthesis takes place
  • Chlorophyll - The green pigment contained in the chloroplasts
  • Permanent vacuole - Space in the cytoplasm filled with cell sap
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18
Q

What is the difference between an animal cell and plant cell?

A

Plant cells make their food by photosynthesis, they don’t move their bodies about from one place to another and they are a lot bigger,

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19
Q

Required practical: Looking at cells

A

https://www.youtube.com/watch?v=SX6mow1AExI

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20
Q

Eukaryotic cells

A

Cells from eukaryotes that have a cell membrane, cytoplasm and genetic material enclosed in the nucleus

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21
Q

Example of a eukaryotic cell

A

animal and plant cells

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22
Q

What is genetic material?

A

is a chemical called DNA and this forms structures called chromosomes that are contained within the nucleus

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23
Q

Prokaryotic cells

(Include: definition what the cell looks like)

A

From Prokaryotic organisms have a cytoplasm surrounded by a cell wall that does not contain cellulose. The Genetic material is a DNA loop that is free in the cytoplasm and not enclosed by a nucleus. Sometimes there are one or more smaller rings of DNA called plasmids.

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24
Q

Example of a prokaryotic cell

A

Bacteria… Single-celled living organisms

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25
Q

Can Bacteria be Harmful?

A

Yes… They can cause diseases in humans and other animals and also plants. They can also decompose and destroy stored food.

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26
Q

Relative sizes examples

A
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27
Q

What happens as an organism develops?

A

The cells differentiate to form different types of cells

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28
Q

What happens as an animal cell differentiates to form a specialised cell?

A

It acquires different sub-cellular structures to enable it to carry out a certain function.

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29
Q

Name examples of specialised cells…

A

Nerve cells, muscle cells and sperm cells

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30
Q

Nerve Cell Diagram

A

Specialised to carry electrical impulses around the body of an animal. Provide rapid communication system between the different parts of the body which have several adaptations including:

  • Lots of dendrites to make connections to other nerve cells
  • Axon carrying the nerve impulses from one place to another
  • Synapses are adapted to pass the impulses to another cell/between a nerve cell and muscle cell
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31
Q

Muscle Cell Diagram

A

Specialised cells that contract and relax in pairs to move the bones of the skeleton. Smooth muscle cells from one of the layers of tissue in your digestive system and they contract to squeeze food through your gut…

Adaptation:

  • Contain special proteins that slide over each other making fibres contract
  • Contain Mitochondria to transfer energy needed for the chemical reactions to take place as the cells contract and relax
  • Can store glycogen (chemical that can be broken down and used in a cellular respiration by the mitochondria to transfer energy needed for the fibres to contract)
32
Q

Sperm Cell Diagram

A

Usually released a long way from the egg they are going to fertilise. Contain the genetic information from the male parent.

Adaptations:

  • Long tail whips from side to side to help move the sperm through water etc.
  • Middle section is for mitochondria, transfer of energy needed for the tail to work
  • Acrosome stores digestive enzymes for breaking down the outer layers of the egg, pointy
  • Large nucleus contain genetic info to be passed on
33
Q

Specialisations in plant cells examples…

A

Root hair cells, Photosynthetic cells, Xylem cells, Phloem Cells

34
Q

Root Hair cells diagram…

A

The role is to take in lots of water, close to xylem tissue. Mineral ions are moved into the root hair cell by active transport…

Adaptations:

  • Greatly increase the surface area available for water to move into the cell
  • Have a large permanent vacuole that speeds up the movement of water by osmosis
  • Have many mitochondria that transfer the energy needed for the active transport of mineral ions
35
Q

Photosynthetic cell diagram…

A

Can make their food through photosynthesis.

Adaptations:

  • Contain specialised green structures called chloroplasts containing chlorophyll which traps the light needed for photosynthesis
  • Positioned in numerous layer in the leaves so can absorb as much light as possible
  • Large permanent vacuole that helps keep the cell rigid as a result of osmosis
36
Q

Xylem Cell Diagram…

A

transport tissue in plants that carries water and mineral ions from the roots to the highest leaves and shoots. Also supports the plant.

Adaptations:

  • The cells are alive when first formed, but a special chemical called lignin builds up in spirals in the cell walls. The cells die and form long hollow tubes that allow water and mineral ions to move easily through them, from one end of the plant to another
  • Spirals and rings of lignin in the xylem cells make them very strong and help them withstand the pressure of water moving up the plant. Also help support the plant stem
37
Q

Phloem cell diagram…

A

Specialised transport tissue that carries the food made by photosynthesis around the body of the plant. Dissolved food can move up and down the phloem tubes where it is needed.

Adaptations:

  • Cell walls between the cells break down to form special sieve plates.
    • allow water carrying dissolved food to move freely up and down the tubes to where it is needed
  • Lose a lot of their internal structures but they are supported by companion cells that keep them alive - mitochondria
38
Q

Diffusion example diagram… how it works…

A
39
Q

Diffusion…

(Include: its net movement, why does it take place, what happens if it is a high or low concentration difference, what is it called with the difference of the 2 concentrations, does diffusion occur up or down the concentration gradient, what effect does temperature have on the rate of diffusion)

A
  • Has a net movement from a higher concentration to a lower concentration
    • Net movement = particles moving in - particles moving out
  • It takes place because of the random movement of particles, the motion of the particles causes them to bump into each other, moving them around.
  • If it is a high concentration difference between the two, then diffusion will take place quickly, particles will move randomly towards the area of low concentration only few will move in the other direction. If there is a small difference, then it will take place very slowly. The greater difference in the concentration, the faster the rate of diffusion.
  • A concentration gradient is the difference between the 2 concentrations
  • It occurs down the concentration gradient
  • An increase in the temperature means that particles in it will move around more quickly, making diffusion happen quicker.
40
Q

Where does anaerobic respiration take place?

A

Mitochondria

41
Q

Diffusion in living organisms

A

Dissolved substances (i.e. glucose and urea) and gases (i.e. Oxygen and CO2) move in and out of cells by diffusion

42
Q

Partially Permeable membrane

A

A membrane that allows only certain substances to pass through, water

43
Q

Dilute

A

make (a liquid) thinner or weaker by adding water or another solvent to it.

44
Q

Concentrated

A

present in a high proportion relative to other substances; having had water or other diluting agent removed or reduced.

45
Q

Osmosis

A

The diffusion of water through a partially permeable membrane from a dilte solution (high concentration of water) to a concentrated solution (low concentration of water) down a concentration gradient.

46
Q

Diagram of Osmosis

A
47
Q

Isotonic

A

(osmosis) a solution that is the same concentration as the cell contents

48
Q

Hypertonic

A

(osmosis) a solution that is more concentrated than the cell contents

49
Q

Hypotonic

A

(osmosis) a solution that is less concentrated than the cell contents

50
Q

Osmosis in animals

A
51
Q

Osmosis in plants

A
52
Q

Turgor

A

The pressure inside a plant cell exerted by the cell contents pressing on the cell wall

53
Q

Required Practical: investigating osmosis in plant cells

A

https://www.youtube.com/watch?v=oieXYuQm_xE

54
Q

Active Transport

A

The movement of substances from a dilute solution to a more concentrated solution against the concentration gradient across a partially permeable membrane requiring energy from respiration.

55
Q

Graph for active transport

A

If a cell respires and releases lot of energy = can carry out lots of active transport

56
Q

What is a plasmid?

A

Small rings of DNA

57
Q

Why is active transport needed?

A

To carry a molecule across the membrane and then return to its original position, the energy produced during respiration. Uses energy releases from food in respiration to provide the energy required.

58
Q

Examples of active transport

A

Root hair cells in plants and cells lining your gut. Cells involved in a lot of active transport usually have many mitochondria to release the energy they need.

59
Q

Importance of active transport…

A

Allows plant root hairs to absorb mineral ions required for healthy growth from very dilute solutions in the soil against the concentration gradient. It enables sugar molecules used for cell respiration to be absorbed from lower concentrations in the gut into the blood where the concentration of sugar is higher.

60
Q

Active transport diagram…

A
61
Q

Single-Celled organisms…

A

Have a relatively large surface area to volume ratio so all necessary exchanges with the environment take place over this surface.

62
Q

What happens to the surface area to volume ratio when the living organisms get bigger and more complex?

A

The surface area to volume ratio gets smaller, making it increasingly difficult to exchange materials quickly enough with the outside world:

  • Gases and food molecules can no longer reach every cell inside the organism by simple diffusion
  • Metabolic waste cannot be removed fast enough to avoid poisoning the cells
63
Q

Adaptations for exchanging materials: THe effectiveness of an exchange surface can be increased by…

A
  • Having a large surface area over which exchange can take place
  • Having a thin membrane or being thin to provide a short diffusion path
  • In animals: efficient blood supply moves the diffusing substances away from the exchange surfaces and maintains a steep concentration (diffusion) gradient
  • In animals: being ventilated makes gas exchange more efficient by maintaining steep concentration gradients
64
Q

In multicellular organisms…

A

many organs are specialised with effective exchange surfaces

65
Q

Features of exchange surfaces

A

Large surface area, thin walls (give short diffusion distances)

66
Q

Examples of adaptations

A
67
Q

Stem cell?

A
68
Q

How can stem cells cure diseases?

A

Stem cells transferred from bone marrow of a healthy person can replace faulty blood cells in the patient who receives it.

69
Q

What can embryonic stem cells do?

A

Replace faulty genes in sick people - make insulin-producing cells for people with diabetes, nerve cells for paralysed people etc.

70
Q

Reasons against stem cell research…

A
  • Feel that human embryos shouldn’t be used for experiments since they’re a potential human life, though others think it is better curing the living and sick than the rights of an embryo.
  • Embryos are unwanted ones from fertility clinics
71
Q

What can stem cells produce?

A

Clones… identical things, plants - rare species… desired crops

72
Q

Diagram of gas exchange…

A
73
Q

Single-celled organisms

A

Gases and dissolved substances that can dissolve directly into or out of the cell across the cell membrane = large surface area compared to volume

74
Q

Multicellular Organisms

A

A smaller surface area to its volume. Not enough substances can diffuse from their outside surface to supply their entire volume.

75
Q

How are exchange surfaces adapted to maximize its effectiveness?

A
76
Q

What is Villi?

A
77
Q

Structure of the leaves…

A
  • Carbon Dioxide diffuses into the air spaces within the leaf then diffuses into the cells where photosynthesis takes place

GCSE Combined Science: Biology (Higher) (5 decks)

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