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GCSE Biology Paper 1 v2 > Cell Biology > Flashcards

Cell Biology Flashcards

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1
Q

What are cells?

A

They are the building blocks of living organisms.

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2
Q

What are the two types of cells?

A

> Prokaryotic - Single celled organisms

> Eukaryotic - the cells that make up a multi-cellular organism

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3
Q

What are the organelles in an animal cell?

A
  • Nucleus
  • Cytoplasm
  • Ribosomes
  • Cell membrane
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4
Q

What are the functions of the organelles in animal cells?

A

> Nucleus - contains genetic information and controls activity within the cell
Cytoplasm - gel-like substance where most of the chemical reactions take place in the cell
Cell membrane - holds the cell together and controls what goes in and out
Mitochondria - Where aerobic respiration occurs
Ribosomes - where proteins are made (proteinsynthisis)

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5
Q

What are the unique organelles in a plant cells (not in animal cells)?

A
  • Cell Wall
  • Permanent vacuole
  • Chloroplast
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6
Q

What are the functions of the unique organelles in a plant cell?

A

> Cell wall - made of cellulose, supports the cell
permanent vacuole - contains cell sap, a weak solution of sugar and salts,it acts as a storage for materials and waste
Chloroplast - Where photosynthesis takes place, light is absorbed here in the chlorophyll for photosynthesis as well. It also gives the plant a green colour.

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7
Q

What are examples of a Eukaryotes (made of Eukaryotic cells)?

A
  • Plants

- Animals

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8
Q

What are examples of Prokaryotes?

A
  • Bacteria

- Algae

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9
Q

What are the organelles in a bacteria cell?

A
  • Cytoplasm
  • Cell wall
  • Cell membrane
  • Plasmids (Small rings of DNA)
  • Strands of DNA
  • Ribosomes
  • Mitochondria
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10
Q

What are the differences between animal and bacteria cells?

A
  • Animal cells don’t have a cell wall

- Animal cells have a nucleus, Bacteria have lose strands of DNA and plasmids,

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11
Q

What are the differences between plant and bacteria cells?

A
  • Bacteria don’t have a permanent vacuole.
  • Bacteria don’t have chloroplast
  • Bacteria don’t have a nucleus,they have lose strands of DNA and plasmids
  • Bacteria don’t have mitochondria
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12
Q

How do you calculate magnification?

A

Magnification = image size/ real size

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13
Q

What are the two types of microscopes?

A
  • Light

- Electron

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14
Q

What are the differences between an electron microscope and light microscope?

A
  • Electron microscopes have a much high magnification and higher resolutions
  • Electron microscopes use electrons to form an image, whereas, light microscope use light.
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15
Q

How do you prepare a slide?

A
  • Add a drop of water to a clean slide,
  • cut of an onion skin and use tweezers to separate the epidermis tissue,
  • Place the tissue onto the slide,
  • Add a drop of iodine,
  • carefully place a top slide onto the onion tissue, make sure there are no air bubbles do you can see clearly through the microscope.
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16
Q

What does it mean for a cell to become specialised?

A

Cells differentiate, this is the process where the cell changes to serve a particular function. The cell will change its internal and external structure in order to adapt and become efficient for its function.
Stem cells differentiate to become specialised .

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17
Q

How are sperm cells specialised for reproduction?

A
  • long tail and streamline head to make swimming to the egg efficient,
  • has lots of mitochondria so that it has the energy to swim,
  • carries enzymes in its head to digest through the eggs membrane.
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18
Q

How are nerve cells specialised for rapid signalling?

A
  • They are long so they cover more distance,

- Have branched connections at the end so they can connect to other nerve cells to form a network

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19
Q

How are muscle cells specialised for contraction?

A
  • Long so they have more space to contract,

- Contain lots of mitochondria for energy

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20
Q

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

A
  • Large surface area
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21
Q

How are phloems and xylems specialised for transporting substances?

A

Xylems:
- Long
- Hollow,
- Strong and withstand pressure because of spiral and ring structures called lining support the xylems,
Phloems:
- The cell walls between each of the phloems break down to form sieves, this allows water to flow through the phloem tubes easily,
- The mitochondria of supporting companion cells move the water and minerals up the phloem

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22
Q

What are chromosomes?

A

Coiled up lengths of DNA

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23
Q

How many chromosomes are in the human body?

A

46 chromosomes (23 pairs)

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24
Q

What is DNA?

A

deoxyribonucleic acid, a molecule that contains genetic information, made up of: a phosphate + sugar + base.

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25
Q

What is the purpose of the cell cycle do?

A

Makes new cells for growth, development and repair

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26
Q

What are the steps of mitosis?

A
  • Everything in the cell replicates
  • The genetic information becomes chromosomes in the nucleus
  • The nucleus membrane dissipates
  • The chromosomes line up down the middle
  • Spindle fibres pull the chromosomes in half to the other side of the cell, each half is identical to the other
  • The cell membrane pinches and splits in two
  • A nuclear membrane forms around the chromosomes, which turn back into genetic information
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27
Q

What is binary fission?

A

The process where prokaryotic cells replicate

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28
Q

How does binary fission work?

A
  • Everything in the cell doubles
  • The cell grows
  • The strands of DNA move to opposite poles of the cell
  • The cytoplasm begins to divide and new walls start to form
  • The cytoplasm splits into two daughter cells, they have identical genetic information, but, can have any number of plasmids
29
Q

What can accelerate the rate of binary fission?

A
  • Temperature

- abundance of nutrients

30
Q

How do you calculate the number of bacteria in a population?

A
  • Find out the number of divisions that have taken place,
  • 2^(that number)
    e.g. it has been 2.5 hours, a cell division happens every 30 mins, how many cells?
    2.5hrs = 150mins
    150/30 = 5
    2^5 = 32 cells
31
Q

What is the zone of inhibition?

A

The area around an antibiotic that is clear of bacteria, this shows the effectiveness of the antibiotic. The larger the zone of inhibition, the greater the effect of the antibiotic.

32
Q

What is a culture medium?

A

What bacteria is grown in, it contains all the necessary nutrients for growth (carbohydrates, minerals, proteins and vitamins)

33
Q

How do you culture bacteria?

A
  • First put a petridish with some agar gel in an autoclave, in order to sterilise it,
  • Next use an inoculating loop to transfer the bacteria that is being culture into the sterile agar gel, work over a flame so that the loop stays sterile,
  • Cover the petridish using a lid,
  • Tape the edges of the lid so that no bacteria can come in or out, not too tightly though because oxygen is needed to make sure that no anaerobic bacteria (harmful) grow.
  • Label the bacteria you are culturing, not on the lid but on the underside of the petridish
  • Store the petridish upside down so that no condensation can fall onto the agar gel
  • This is stored in an incubator to culture, in a school lab it is cultured at 25°C.
34
Q

How do you test for the effectiveness of antibiotics?

A
  • Put a paper disk with the antibiotic onto the cultured bacteria,
  • The size of the zone of inhibition determines how effective it is, the bigger the area the more effective.
  • Always put a plane paper disk onto the culture as well to makes sure that nothing in the paper kills the bacteria, just the antibiotic
35
Q

What are the aseptic techniques?

A
  • The culture medium and petridish must be sterile before use (using an autoclave) so that no other bacteria is in the dish or agar gel when culturing.
  • When using an inoculating loop you must work under the flame so it stays sterile,
  • Tape on the lid of the petridish tightly to stop the entrance and exit of bacteria into the petridish
  • The petridish must be stored upside down so that no condensation drips onto the agar gel
36
Q

What are the two different types of stem cells?

A

> Embryonic - can turn into any type of cells

> Adult - can only turn into certain cells

37
Q

What is a stem cell?

A

An undifferentiated cell, they can divide to produce more undifferentiated cells.

38
Q

Where are embryonic stem cells found?

A

The early stages of a human embryo, they can turn into any type of cells because all human cells originate form embryos.

39
Q

Where are adult stem cells found?

A

Bone marrow

40
Q

What are some uses of stem cells?

A

Can be used to cure diseases because they can replace dead cells,

  • Embryonic stem cells can be used to cure diabetes by creating insulin-producing cells,
  • Embryonic stem cells can make nerve cells for paralysed people who have spinal injuries.
  • Embryonic stem cells can be made to have the same genes as the patient so they are not rejected by the patient
41
Q

What are the risks of stem cells?

A

They may carry viruses from when being cultured in the lab.

42
Q

Why are some people against the use of embryonic stem cells?

A
  • It is experimenting using potential human life,
  • it means that the patients life is more valuable than the embryos (the potential life)
  • Some people feel that scientists should try look for other sources of stem cells,
  • However, most embryos experimented on are unwanted and would probably be destroyed, but campaigners against embryonic stem cells usually want the fertility clinics (where the embryos come form) to be banned too.
43
Q

Where are the stem cells found in plants?

A

Meristems

44
Q

What are the uses of meristem tissue

A
  • Tissue in the meristem differentiate throughout the plants life, can reproduce the plants quickly
  • meristem’s can produce clones of plants so that they reproduce very quickly
  • They can be used to create clones of rare plants to prevent extinction,
  • Meristem can also be used to grow crops of identical plants that have desired features like disease resistance.
45
Q

What is the main difference between differentiation in plants and animals?

A

Meristem tissue differentiate throughout the plants life whereas animal cells only differentiate at the start of the humans life.

46
Q

What is diffusion?

A

The net movement of particles from a high concentration to a low concentration (across a concentration gradient)

47
Q

What are examples of molecules that are too big to diffuse into a cell?

A
  • Starch

- Protein

48
Q

What are some examples of molecules small enough to diffuse into cells?

A
  • Glucose
  • Amino acids
  • water
49
Q

What is osmosis?

A

The movement of water molecules across a partially permeable membrane form a high concentration to a low concentration (across a concentration gradient)

50
Q

How can you use osmosis to test the effect of sugar solutions on potato cylinders?

A
  • Cut up a potato into identical cylinders,
  • Measure the mass of each potato cylinder and record them separately,
  • Put each cylinder in a sugar solution of different concentration, one solution will be very concentrated, one cylinder will also be put into pure water
  • Put a lid on and keep them in the solution for 24 hours
  • Take out the potato cylinders and dry them after the 24 hours is up,
  • Measure the new weight,
  • If the weight has increased, water has gone into the potato by osmosis, this happened because the potato had a lower concentration of water in comparison to the solution outside,
  • If the weight decreased, then water left the potato because their was a higher concentration of water inside the potato in comparison to the solution outside.
  • REMEMBER TO USE DATA IN THE EXAM WHEN EXPLAINING ANSWERS
51
Q

When is osmosis commonly used?

A
  • Turning guard cells in leafs turgid

- Diffusion of water into cells

52
Q

What is active transport?

A

The movement of molecules from an area of low concentration to an area of high concentration (against the concentration gradient) using energy

53
Q

When is active transport commonly used?

A
  • Root hair cells use it in plants to absorb minerals ion from the soil.
  • Taking glucose from the gut and from kidney tubules so that we always have glucose for energy
54
Q

When is diffusion used in humans?

A
  • Oxygen and CO2 between the alveoli and capillaries

- Urea diffuses from cells into blood plasma so it is sent to the kidney for removal from the body via a fat wazz

55
Q

What is the general rule for SA:V (Surface area:Volume)?

A

The smaller the object, the bigger SA:V ratio it will have, this makes it very effective for diffusion.

56
Q

How are the alveoli and villi adapted for diffusion?

A
  • Thin walls
  • Large surface area, more diffusion at once
  • Surrounded in capillaries for easy access to the blood stream
  • Alveoli are ventilated so they can easily get rid of waste CO2 and bring in new O2
57
Q

Why is it more efficient for humans to diffuse gases and minerals into our bodies using exchange surfaces?

A

Humans have a small SA:V ratio so it is more efficient if we diffuse necessities into our body using exchange surfaces because they have a high SA:V ratio so more can be diffused into our bodies at once.
We also have millions of villi in our small intestine and thousands of alveoli in our lungs so we have a very large surface area for very efficient diffusion.

58
Q

How does the alveoli exchange gases and what gases exchange in the alveoli?

A
  • When Oxygen rich air is breathed in through the lungs, the Oxygen diffuses form a high concentration (the air in the alveoli) into the capillaries which carry oxygenated blood.
  • The oxygen binds to the haemoglobin in the blood cells to create oxyhaemoglobin and the blood is sent back to the heart.
  • As this happens, CO2 diffuses from the capillaries (high concentration) to the alveoli so it can be exhaled with the now CO2 rich air
59
Q

How are leaves adapted for diffusion?

A
  • They have air spaces in the Spongy mesophyll so that gases can diffuse easily,
  • They have loads of stomata (small holes) on the underside of the leaf so gases can be exchanged form inside the leaf and water vapour can be let out (transpiration)
  • Guard cells control if the stomata are open or closed so that no excess CO2 is taken in by the plant and no oxygen or water vapour escapes from the plant whilst it is not photosynthesising.
60
Q

What is the structure of the leaf?

A
  • Waxy cuticle
  • Upper epidermis
  • Palisade Mesophyll
  • Spongy Mesophyll
  • Lower epidermis (guard cells and stomata)
61
Q

What is the function of the waxy cuticle?

A
  • Stops water loss from the leaf from evaporation (transpiration)
62
Q

What is the function of the upper epidermis?

A
  • Transparent so light can get through to the Palisade Mesophyll layer
63
Q

What is the function of the Palisade Mesophyll?

A
  • Lots of cells that conduct photosynthesis,
  • They are cylindrical so that they cover the most surface area possible so that more photosynthesis can occur
  • They have lots of chloroplast for photosynthesis
  • Absorb light for photosynthesis
64
Q

What is the function of the Spongy Mesophyll?

A
  • Have air gaps for better gaseous exchange,
65
Q

What is the function of the lower epidermis?

A
  • Has guard cells and stomata to control gases entering and exiting the cell
66
Q

How do guard cells become turgid and what happens when the do?

A
  • potassium ions are pumped into the guard cells,
  • This creates a low concentration of water in the guard cells, compared to the surrounding cells,
  • Water diffuses into the guard cells from surrounding cells and makes the guard cell swell (become turgid)
  • This makes the guard cell open up and allow the loos of water and gases to enter and exit the leaf.
67
Q

Why are there less stomata on the top of the cells?

A

To prevent water loss in the plant from evaporation (from transpiration)

68
Q

How are gills adapted for gaseous exchange?

A
  • They have large surface area as they are made of lots of plates called gill filaments,
  • Gill filaments are covered in tiny structures called lamellae to further increase surface area
  • Lamellae have a large blood supply (capillaries)
  • Gills have a very thin wall to make diffusion distance shorter and easy.

GCSE Biology Paper 1 v2 (5 decks)

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