Micro-organisms (+also evolution)

Question 1

What are the conditions of life?

Answer 1

Movement
Respiration
Sensitivity

Control internal conditions
Reproduction
Nutrition
Growth

Question 2

What are plants?

Answer 2

• have chloroplasts and cellulose cell walls

* store carbs as starch or sucrose

Question 3

What are animals?

Answer 3

• no chloroplasts/cell walls/PS
• usually have nervous coordination
• can move from one place to another
• often store carbs as glycogen

Question 4

What are fungi?

Answer 4

• no PS
• body as mycelium w thread like structures for many hyphae. These have many nuclei
• some single celled
• cell walls of chitin
• fed by extra cellular secretion of digestive enzymes onto food material and absorption of organic products (saprotrophic nutrition)

Question 5

What are bacteria?

Answer 5

• single celled
• cell wall, membrane, cytoplasm and plasmids, but no nucleus. Instead circular chromosomes of RNA
• some carry PS but most feed off other organisms

Question 6

What are protoctists?

Answer 6

• single celled

* some, like amoeba have animal cell features but other like chlorella have features like plant cells

Question 7

What are viruses?

Answer 7

• smaller than bacteria
• parasitic, can only reproduce inside other things
• no cellular structure, but have a protein coat and DNA or RNA

Question 8

What is a pathogen?

Answer 8

Microbes that can cause disease. Can be fungi, protoctists, bacteria or viruses

Question 9

How does blood clotting work?

Answer 9

• need to speak wound quickly to avoid blood loss and stop pathogens entering
• ∴ when a blood vessel breaks platelets (small cells in blood) stick together and activate formation of a mesh of proteins called fibrin
• more platelets and RBCs get caught ∴ scab scab is formed to seal cut

Question 10

What defences does the body have against pathogens?

Answer 10

Respiratory system:
Mucus, ciliates epithelial cells
Eyes:
Enzymes in tears
Skin:
Waterproof, impermeable
Nose:
Nasal hair, mucus, sneezing
Mouth:
Salivary enzymes, coughing reflex
Stomach: acid
Vagina: acidic secretions

Question 11

What are phagocytes?

Answer 11

• WBCs that engulf pathogens
• easily pass through cell walls and move towards pathogens, then engulf them, and release enzymes to digest and destroy it
• this is called phagocytosis

Question 12

What are lymphocytes?

Answer 12

• WBCs that make antibodies/antitoxins
• antigens are substances on the surface of a pathogen- different pathogens have different ones
• antibodies are proteins that can recognise and bind to antigens- different lymphos make ones specific to a particular antigen
• when lymphos meet pathogens w AGs they know they divide quickly and make many ABS to bind, which destroys the pathogen and can help phagos to to engulf and digest pathogen more easily
• bacteria release toxins to makes us ill ∴ ATs made by lymphosto neutralise actions of toxins

Question 13

How does vaccination work?

Answer 13

• vaccines contain dead or less infectious versions of AGs
• trigger lymphocyte activation- antibody production and formation off memory cells
∴ in future antibody production will happen sooner, faster and in great quantity as mem cells exist

Question 14

How do antibiotics work?

Answer 14

• destroy cell wall, e.g.g penicillin

* or stop protein synthesis ∴ no genere replication ∴ no cell division, e.g. Tetracycline

Question 15

How does antibiotic resistance happen?

Answer 15

1. Severe infection
2. Antibiotics stopped
3. Immune system can’t cope w all the pathogens. They multiply
4. Many resistant bacteria
5. Even w antibiotics immune system can’t stop due to all resistant bacteria
6. Infection not cleared

Question 16

How do we use Microorganisms to create beer?

Answer 16

• yeast anaerobically respires (fermentation) to make ethanol
Glucose ⇒ CO2 + alcohol + some energy

Question 17

How do we use Microorganisms to create yoghurt?

Answer 17

• anaerobic respiration of lactobacillus
Lactose ➯ lactic acid
• lactic acid lowers pH meaning harmful pathogens can’t enter
• also makes milk clot and denatures the milk enzymes to give it its sharp taste
1. Milk pasteurised to kill bacteria, roughly 85°C
2. Milk is homogenised
3. Milk is cooled and incubated w lactobacillus
4. Milk incubated for several hours
5. Fruit/flavours added

Question 18

What is an investigation to measure CO2 production by yeast?

Answer 18

Get two test tubes, with a bung and a tube leading from on to the other. Place yeast and sugar solution in the one with the bung, and limewater or hydrogen carbonate indicator (orange to yellow in CO2 in the other). This will change if the yeast respires and produces CO2. Repeat, but with a layer of liquid paraffin covering the yeast and sugar solution to get anaerobic respiration.

Question 19

What is the point of the steam inlet in a fermenter?

Answer 19

Hot steam sterilises the inside of the fermenter- this is for aseptic conditions to prevent contamination by unwanted Microorganisms

Question 20

What is the point of the nutrient inept in a fermenter?

Answer 20

Allows sterile nutrias to enter fermenter- microbes need it to grow and reproduce

Question 21

What is the point of the water jacket with cooling water in a fermenter?

Answer 21

Keeps temp inside constant ∵ Microorganisms for best at an optimum temp

Question 22

What is the point of the air inlet in a fermenter?

Answer 22

Provides a source of oxygen, as Microorganisms need it for aerobic resp

Question 23

What is the point of the filter on air inlet in a fermenter?

Answer 23

Stops Microorganisms getting in fermenter ∴ prevents contamination

Question 24

What is the point of the stirring paddles in a fermenter?

Answer 24

Keeps the mixture in the fermenter agitated ∴ mixes Microorganisms w nutrients and keep temp even

Question 25

Why do some characteristics become more common?

Answer 25

• variation due to random mutations
• selection pressure, e.g. Food, predators, disease, climate, mate exists
• those best suited due to the variation, survive
• they survive to pass on their genes, while others don’t
• ∴ these characteristics become more common

Question 26

What is selective breeding? What are examples of desirable characteristics?

Answer 26

Breeding only those individuals w desirable characteristics. Artificial selection
E.g. High yield, disease resistant, flavour, looks (plants), high growth rate, looks, milk, disease resistant (animals)

Question 27

How do you create a cow w a high milk yield?

Answer 27

Select cow w high milk yield and breed w bull from fam of high milk yield (maybe use artificial insemination)
∴ select offspring w high milk yield and repeat process

Question 28

Why are viruses not alive?

Answer 28

Can only reproduce within other cells
Don’t grown or move
Don’t respond to stimuli