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GCSE BIOLOGY AQA > B1-Cell Biology > Flashcards

B1-Cell Biology Flashcards

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1
Q

Organisms can be what two types of cells?

A

Prokaryotes or Eukaryotes

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2
Q

All living things are made from what?

A

Cells (basic building blocks of life)

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3
Q

Describe the characteristics of Eukaryotic cells

A

Eukaryotic cells are complex and include all animal and plant cells. Eukaryotes are organisms made from eukaryotic cells. All eukaryotic cells contain a cell membrane, cytoplasm and a nucleus

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4
Q

Describe the characteristics of Prokaryotic cells

A

Prokaryotic cells are smaller and simpler. A prokaryote is a prokaryotic cell as it’s a single-celled organism. Prokaryotic cells do not have a nucleus. Instead their genetic material is stored in a single DNA loop in the cytoplasm, they may also contain plasmids but have NO mitochondria or chloroplasts

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5
Q

What are the different parts of the cell called?

A

Sub-cellular structures

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6
Q

What is the function of the cell membrane?

A

It separates the interior of the cell from the environment outside, it is selectively permeable, holds the cell together and controls what enters and leaves the cell

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7
Q

What is the function of the cytoplasm?

A

It is a jelly-like substance located just outside the nucleus, and by using enzymes, it’s where the cell’s chemical reactions take place

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8
Q

What is the function of the nucleus?

A

It is the control centre of the cell that contains the genetic material in the form of chromosomes and control the activities of the cell. Genetic material is stored in DNA

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9
Q

What is the function of plasmids?

A

They are small rings of DNA which replicate and move between cells so genetic information can be shared.

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10
Q

What does selectively permeable mean?

A

Something that is selectively permeable can control the substances which move through it,

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11
Q

Turn this standard from number back into a normal number 2.5 x 10-3

A

2.5x10-3= 0.025, because it goes to the right add the -

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12
Q

Turn this number into standard form 25000

A

25000= 2.5x10 4, because it goes to the right is stays positive

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13
Q

What is the function of ribosomes?

A

Ribosomes are responsible for synthesising (making proteins)

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14
Q

What sub-cellular structures are present in plant cells but not animal cells?

A

Chloroplasts, vacuole and cell wall

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15
Q

What is the function of mitochondria?

A

They are responsible for providing energy for the cell as aerobic respiration happens here

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16
Q

Plant cells can..?

A

Be reproduced by cuttings, retain the ability to differentiate and create new tissues

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17
Q

What sub cellular structures are present in animal cells?

A

Cell membrane, Nucleus, Ribosomes, Mitochondria, Cytoplasm

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18
Q

Animal cells can..?

A

Rarely create new tissues, have to reproduce sexually and differentiate in the embryo

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19
Q

What is the function of chloroplasts?

A

They contain chlorophyll for photosynthesis

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20
Q

What is the function of a large permanent vacuole?

A

Fluid-filled sac that contains water and sap

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21
Q

What is the function of a cell wall?

A

Made of cellulose it surrounds the cell and increases the structural strength

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22
Q

When does differentiation occur in cells?

A

When cells acquire different sub-cellular structures.

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23
Q

How many additional sub-cellular structures do plant cells have compared to animal cells?

A

3

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24
Q

Do animal cells divide?

A

Yes usually to repair existing tissues

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25
Q

What are flagella?

A

Whip-like structures that are used for movement

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26
Q

What is a single loop of DNA?

A

The genetic material of the cell

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27
Q

Give an example of a eukaryotic cell

A

Plant and animal cells

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28
Q

Give an example of a prokaryotic cell

A

Bacterial cell

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29
Q

What happens when a cell differentiates?

A

It becomes a different type of body cell

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30
Q

Where are digestive enzymes located?

A

They are found at the tip of the head of sperm cells in the acrosomes. The enzymes help to penetrate the egg.

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31
Q

What is differentiation?

A

Differentiation is the process by which a cell changes to become specialised. As cells change, they develop different sub-cellular structures and turn into different types of cells. This allows them to carry out specific functions

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32
Q

What is differentiation in animal cells?

A

Cell differentiation is rare in mature animals. Their cells mostly divide to replace cells and repair damaged tissues. New tissues are rarely created through differentiation. Primarily happens in human embryos

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33
Q

What is differentiation in plant cells?

A

Plants keep their ability to differentiate throughput their life and are always able to create new tissues

34
Q

How are sperm cells specialised for reproduction?

A

The function is to get the male DNA to the female DNA. sperm cells have three main parts: the head, the middle section, and the flagellum

35
Q

How is a sperm cell’s middle section specialised?

A

This is filled with mitochondria to provide energy for the sperm to travel a long distance to reach the egg

36
Q

How is a sperm cell’s flagellum specialised?

A

This is used for the cell’s motion, allowing sperm to travel towards the egg cell. Also known as the flagellum

37
Q

How is a sperm cell’s head specialised?

A

This contains the sperm cell’s nucleus, which carries one half of an organism’s genetic material. This combines with the egg’s half of genetic material to fertilise the egg

38
Q

How is a sperm cell’s acrosome specialised?

A

This is at the tip of the head and contains an enzyme needed to penetrate (break into) an egg cell

39
Q

How are nerve cells specialised for rapid signalling?

A

A nerve cell, or neurone, is an animal cell. This makes it a eukaryotic cell.Nerve cells transfer electrical signals around the body. These impulses travel very fast, and occur in a fraction of a second. They have three main features: axon, Myelin sheath, Dendrites

40
Q

How is a nerve cells axon specialised?

A

Part of the cell that electrical signals travel along.

Nerve cells have a long axon. This increases the distance that electrical signals can travel

41
Q

How is a nerve cells Myelin sheath specialised?

A

A sheath made of a material called myelin surrounds the axon of the nerve cell. This stops the electrical nerve signals leaking out of the nerve cell.
This increases the speed of transmission (travel) of electrical signals

42
Q

How is a nerve cells Dendrites specialised?

A

Branches of a nerve cell.
Several dendrites spread outwards from the cell body to transfer electrical messages to other neurons.
Electrical messages travel between neurons at synapses.

43
Q

How are muscle cells specialised for contraction?

A

The function of the muscle cell is to contract quickly. These cells are long so that they have space to contract. They contain both protein fibres and mitochondria

44
Q

How is a muscle cells protein fibres specialised?

A

Protein fibres within the cell can contract allowing the muscle to move.

45
Q

How is a muscle cells mitochondria specialised?

A

A muscle cell contains a lot of mitochondria to generate lots of energy for motion.

46
Q

How are root cells specialised for absorbing water and minerals?

A

Root cells are located on the surface of plant roots which grow into long hairs that stick out of the soil.They have long projections and no chloroplasts because they’re underground.

47
Q

How are root cells long projections specialised?

A

Long projections increase the surface area for water and mineral consumption.

48
Q

How are phloem cells specialised for transporting substances?

A

They transport substances such as food and water around plants. The cells are long and joined end to end to form the tubes. Lignin strengthens the walls. The end walls of Phloem cells contain small holes to allow food products to allow food to move up and down the phloem vessels. Have very little structures so that stuff can flow through them

49
Q

How are the xylem cells specialised for transporting substances?

A

They transport substances like food and water. Xylem cells are hollow in the centre. Made up of a series of dead xylem cells. The end walls of the dead cells are broken to allow water to move through. A substance called lignin strengthens the walls

50
Q

Define resolution

A

Resolution is the ability to distinguish between two separate points in an image or between two or more objects. If two points are close together then a low resolution microscope may not see them as separate objects. Using a microscope with a higher resolution will allow them to see them as different.

51
Q

Define Magnification

A

Magnification tells us how many times bigger an image obtained with a microscope is relative to the real object.

52
Q

How do you calculate magnification?

A

Magnification=magnified size of image/real size of object

53
Q

How do you prepare a slide?

A

Add a drop of water to the middle of the clean slide. Cut up an onion and separated it into layers. Use tweezers to pull off some epidermal tissue from the back of one of those layers. Using the tweezers place the epidermal tissue into the water on the slide. Add a drop of iodine solution to highlight. Place a cover slip on top, stand it upright on the slide, next to the water droplet, carefully tilt and lower it so it covers the specimen.Make sure there are no air bubbles.

54
Q

How does a light microscope work?

A

Light microscopes are higher resolution than the human eye and pass light through the specimen. They allow cells to be seen as separate objects. They allowed scientists to see bacteria for the first time.

55
Q

How does an electron microscope work?

A

Electron microscopes use electrons that pass through the specimen instead of light. It allowed scientists to see sub-cellular structures more quickly.

56
Q

What is the cell cycle?

A

The cell cycle makes new cells for growth, development and repair. The stage of the cell cycle where the cell divides is called mitosis. Multi-cellular organisms use mitosis to replicate cells that have been damaged. The end of the cell cycle results in the two identical daughter cells to the original cell with the same number of chromosomes. There are three different stages: interphase, mitosis, cytokinesis.

57
Q

What are chromosomes?

A

The nucleus contains genetic material in the form of chromosomes. Chromosomes are coiled up lengths of DNA molecules. Each chromosome carries a large number of genes.

58
Q

What happens during interphase?

A

Before the cell divides, the cell has to grow and increase the amount of sub-cellular structures such as mitochondria and ribosomes. It then duplicates its DNA so theres one copy for each new cell. The DNA is copied and forms x-shaped chromosomes.

59
Q

What happens during Mitosis?

A

The chromosomes line up at the centre of the cell and cell fibres pull them apart. Then the arms of each chromosome go to opposite ends of the cell. These become the nuclei of the cell and the nucleus has divided.

60
Q

What happens during cytokinesis?

A

The cytoplasm and cell membrane divide into two new identical daughter cells

61
Q

What are stem cells?

A

Stem cells are undifferentiated which means that they haven’t been specialised to perform a specific function. They can create more stem cells or can differentiate to perform another function. Stem cells can be either found in: bone marrow or embryos. Or for plants in plant meristems.

62
Q

What are embryonic stem cells?

A

Embryonic stem cells can differentiate into most cell types and all of the cell types that will make up an organism.

63
Q

What are bone marrow stem cells?

A

In human adult stem cells can be found in bone marrow. Unlike embryonic stem cells they don’t have the potential to turn into every stem cell, only specific ones like blood cells.

64
Q

What are the advantages of stem cells?

A

Stem cells may be able to cure diseases. For example, 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 be used to replace faulty cells in sick people.

65
Q

What are the disadvantages of stem cells?

A

Some people are against stem cells for ethical issues. They feel that human embryos shouldn’t be used for experiments since they’re potential human lives.

66
Q

What are meristems and how can they be used?

A

In plants stem cells are found in the meristems which is the part of the plant where growth occurs. Throughout the entire life the meristem tissue can differentiate into any type of plant cell. These can be used to produce clones of whole plants quickly and cheaply. They can be used to make more rare species. Also develop desired features for farmers such as disease resistance.

67
Q

What is diffusion?

A

Diffusion is the net random movement of particles from an area of higher concentration to an area of lower concentration. It describes the movements of particles in fluids. Substances can move in and out of cells via diffusion. Factors that will increase the rate of diffusion include: large membrane surface area, high concentration gradient, high temperature.

68
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. The concentration becomes the same on both sides of the membrane, and water molecules move to where there are fewer water molecules.

69
Q

What is an independent variable

A

Variable that is controlled and changed in the experiment.

70
Q

What is active transport?

A

Molecules are transported from a low concentration to a high concentration. The net random movement of particles against a concentration gradient and so energy is required.

71
Q

What is passive transport?

A

Osmosis and diffusion are examples of passive transport. Passive transport does not need energy. The particles move randomly, with a net movement towards an area of lower concentration.

72
Q

Give examples of processes that occur via active transport

A

Sugar absorption in the human gut- active transport allows sugar molecules which are needed for cell respiration, to be absorbed into the blood from the gut, even when the sugar concentration of the blood is higher.

Mineral absorption in plants- active transport in the root hairs of plants allow plants to absorb mineral ions, which are necessary for healthy growth, even though the concentration of minerals is usually lower in the soil than in the root hair.

73
Q

How are root hairs adapted to take in minerals and water?

A

The cells on plant roots grow into hairs which stick out into the soil. Each branch of a root will be covered in millions of these microscopic hairs this gives the plant a large surface area for absorbing water and mineral irons from the soil. Plants need mineral ions for healthy growth. The concentration of minerals is usually higher in the root hair cells than in the soil around them so the root hair cells can’t use diffusion to take up minerals from the soil.

74
Q

Observe the effect of sugar solutions on plant tissues.

A

Potato is cut up into into identical cylinders and get some other beakers with different sugar solutions in them. One should be pure water and another should be a very concentrated sugar solution. Then there are some other concentrations in between. You measure the mass of the cylinders then leave one cylinder in each speaker for 24 hours. Then you take them out dry them and measure their masses again. If the cylinders have drawn in the water by osmosis they all have increased in mass. If water has been drawn out they’ll have been decreased in mass.

75
Q

How do you compare surface area to volume areas?

A

Small organisms normally have higher surface area to volume ratio than larger organisms, this means that diffusion can happen through a large area in small organisms. This makes diffusion useful for transporting molecules through a small organism. Multicellular organisms need a transport system with specialised surfaces to exchange molecules as the cells are too far from the external environment.

76
Q

What are exchange services?

A

Exchange surfaces are surfaces that are adapted to maximise the efficiency of gas and solute exchange across them. They have the following adaptations: blood supply,ventilation ,large surface area and thin membrane.

77
Q

How does gas exchange happen in lungs?

A

The job of the lungs is to transfer oxygen into the blood and to remove water carbon dioxide from it. To do this the lungs contain millions of little air sacs called alveoli where gas exchange takes place. The alveoli are specialised to maximise the diffusion of O2 and CO2. They have:
And enormous surface area, a moist lining for dissolving gases, very thin walls and a good blood supply

78
Q

What are villi and how are they adapted?

A

The inside of the small intestine is covered in millions and millions of these tiny little projections called villi. They increase the surface area in a big way so that digestive food is absorbed much more quickly into the blood. They have: single layer of surface cells, and a very good blood supply to assist quick absorption.

79
Q

How are the stomata adapted?

A

Carbon dioxide defuses into the air spaces within the leaf, then it defuses into the cells where photosynthesis happens. The leaf structure is adapted so that it can happen easily. The underneath of the leaf is is an exchange surface as it is covered in lots of little holes called stomata which the carbon dioxide diffuses in through. The size of this stomata are controlled by guard cells and close the stomata if the plant is loosing water faster than its replaced by the roots. The flattened shape of the leaf increases the area of this exchange surface so that it’s more effective. The air spaces inside the leaf increases the area of the surface so that there is more chance for carbon dioxide to get into the cells.

80
Q

How are gills adapted for gas exchange?

A

The gills are the gas exchange surface in fish. Water enters the fish through its mouth and passes through the gills. As this happens oxygen defuses from the water in the blood in the gills and carbon dioxide diffuses from the blood to the water. Each gill is made of lots of thin plates called gill filaments which give a big surface area for exchange of gas. The gill filaments are covered in lots of tiny structures called lamellae which increase the surface area even more. They have lots of blood capillaries to speed up diffusion. They also have a thin surface layer of cells to minimise the distance that the gases have to diffuse. Blood flows through the lamellae in one direction and water flows over in the opposite direction. This maintains a large concentration gradient between the water and the blood. The concentration of oxygen in the water is always higher that than in the blood, so as much oxygen as possible diffuses from the water into the blood.

GCSE BIOLOGY AQA (9 decks)

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