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