S2 Biology - Body systems and cells 2 Flashcards
What are the three classifications of microorganisms?
Fungi, bacteria and viruses
What do we need to view microorganisms?
A microscope
Which group of microorganisms are the smallest?
Viruses
Which type of microorganisms are the largest?
Fungi
Are bacteria smaller or bigger than fungi?
smaller
Name 4 factors which are essential for microbial growth.
Food source, e.g. glucose (sugar)
Water
Warm temperature
Suitable pH
What is cell division?
Cell dividion is the process by which bacteria and yeast cell reproduce; the parent cell divides into two new identical cells.
Starting with 2 cells which divide every 20 minutes, how many cells would you have after 3 hours?
1024 cells
Working:
2-> 4-> 8-> 16-> 32-> 64-> 128 -> 256 -> 512 -> 1024
A type of bacterial cell divides every 45 minutes. How many cells do you have after 6 hours?
256
Working:
1 -> 2 -> 4 -> 8 -> 16 -> 32 -> 64 -> 128 -> 256
Starting with 17 cells, how many cells do you have after one division?
34 (one division doubles the number of cells)
What is the independent variable?
The factor you are changing in an investigation.
When investigating the effect of pH on the growth of microbes, what variables need to be kept constant (controlled variables)?
Temperature or number of cells at the start or concentration of microbes at the start or type & concentration of food supplied to mircobes
How could you ensure the temperature in an investigation stays the same?
Use a waterbath or incubator
Give an example of a situation where the growth of microbes is restricted to preserve food.
Keeping meat and dairy products at 4 degrees C (in the fridge); drying food (no water for microbes to grow); pickles (low pH prevents growth of microbes)
What microorganisms is used to make bread?
Yeast
What products can be made with the help of yeast?
Bread, beer, wine
What makes dough rise?
The yeast inside the dough is producing carbon dioxide (gas) which makes the dough rise.
What two things does yeast produce when it feeds on sugars which help in the production of drinks?
Alcohol & carbon dioxide
What substances can be used to control the growth of bacteria?
Antibiotics
What does it mean if bacteria are ‘resistant’ to antibiotics?
The antibiotics do not stop the growth of the bacteria (i.e. they do not work against these bacteria).
In which parts of your body can fungi find ideal growing conditions?
Between toes
Under arm pits
Mouth
Reproductive tract
What do you call medicines that treat infections caused by fungi?
Antifungals
What effect does increasing the temperature have on the growth of microbes?
The more the temperature increases the more the microbes grow, until it gets too hot for them and then they stop growing and die.
What is a pathogen?
A pathogen is a disease-causing microorganism
Give 3 examples of pathogens.
Some bacteria, e.g. those causing pneumonia, food poisening or whooping cough;
Some fungi, e.g. those causing athlete’s foot or ringworm
All viruses, e.g. chickenpox, measles, flu
Why does the body have a ‘first line of defence’?
To prevent microbes form entering the body or entering the blood stream.
Give examples of the first line of defence of your body (7)
Nose hairs
Eyelashes
Tears
Stomach acid
Saliva
Cillia & mucus
Skin
Name two types of white blood cells.
Phagocytes & lymphocytes
What is the function of the phagocytes?
Phagocytes surround and engulf pathogens that manage to get into the body, and then destroy them using special chemicals (enzymes).
Which cells engulf pathogens to destroy them?
Phagocytes (a type of non-specific white blood cell)
Why are lymphocytes described as ‘specific’ white blood cells?
Each type of lymphocyte only produces antibodies against a specific type of pathogen; e.g. antibodies produced against the chickenpox virus will only bind to this specific virus but no other virus.
Describe the role of lymphocytes in the immune response.
Lymphocytes target specific pathogens by making antibodies which bind to the antigens (surface structures) on the surface of pathogens; antibodies are specific against one type of pathogen/ antigen.
What is meant by immunological memory?
After an initial infection, when the person come sin contact with the same pathogen again, the lymphocytes make the required antibodies much faster and at higher concentrations as they are already familiar with the pathogen.
The train the body’s immune system, vaccines may contain…
…
weaker forms of pathogens
dead pathogens
parts of pathogens
antigens of pathogens
genetic information for the body to make the pathogen’s antigen (e.g. Covid spike protein)
Is it more or less likely for a pathogen to spread if more people are vaccinated?
It is less likely for a pathogen to spread if more people are vaccinated.
