The Nature and Variety of Organisms Flashcards
What are the characteristics of living organisms?
Movement
Respiration
Sensitivity
Homeostasis
Growth
Reproduction
Excretion
Nutrition
What are the levels of organisation in organisms?
Organelles (Parts of a cell)
Cells
Tissues
Organs
Organ systems
Organism
What organelles are found in both animal and plant cells?
Nucleus
Cytoplasm
Mitochondria
Ribosomes
Cell membranes
What organelles are found only in plant cells?
Cell walls
Large vacuoles
Chloroplasts
What function does the nucleus provide?
Contains the cell’s genetic material and controls the cell’s activities
What does the cell membrane do?
Outer layer of the cell. It allows substances in and out of the cell
What does the cytoplasm do?
Cell’s chemical reactions happen here. It’s a gel-like substance
It contains enzymes which control these reactions
What do the mitochondria do?
Where aerobic respiration takes place
What do the ribosomes do?
Proteins are made here through protein synthesis
What do chloroplasts do?
Photosynthesis happens here. They contain green substances called chlorophyll
What is the cell wall?
A rigid structure made of cellulose which surrounds the cell membrane. It supports the cell and strengthens it
What is a large vacuole?
Supports the cell. Contains cell sap to do this
What is cell differentiation?
The process by which a cell changes to become specialised for a specific job
Why are embryonic stem cells special?
They have the potential to turn into any kind of cell
Do adults have stem cells?
Yes, but they’re only found in certain places, e.g. the bone marrow.
They can only turn into specific cells, like RBC
RBC = Red blood cells
How can adult stem cells be used to cure diseases?
Stem cells transferred from bone marrow of a healthy person can replace faulty blood cells in a sick patient
How can embryonic stem cells be used to cure disease?
Can replace faulty cells. They can also make insulin-producing cells (for those with diabetes) or nerve cells (those who are paralysed)
Why are some people against stem cell research?
Some see embryos as potential human lives, and therefore shouldn’t be used for experiments
What are the main features of plants?
Eukaryotic
Have chloroplasts, therefore photosynthesise
Store carbohydrates as sucrose or starch
What are the main features of animals?
Eukaryotic
Have nervous coordination so can rapidly respond to changes in an environment e.g. can move
Store carbohydrates as glycogen
What are the main features of fungi?
Most are eukaryotic
Have a body called mycelium made up of hyphae
Cell walls made of chitin
Store carbohydrates as glycogen
How do plants feed?
Autotrophicly
How do animals feed?
Heterotrophically
How do fungi feed?
Saprotrophically -> Secrete extracellular enzymes into the area outside their body and dissolve the food
What are some examples of fungi?
Yeast (single-celled)
Mucor
What are the characteristics of protoctists?
Mostly single-celled
Some more like plant cells, others are more similar to animal cells
What are some examples of protoctists?
Chlorella
Amoeba
Plasmodium (causes malaria)
What are the characteristics of bacteria?
Prokaryotes
Don’t have a nucleus, instead they have circular chromosomes of DNA
Both heterotrophic and saprotrophic
What are some examples of bacteria?
Lactobacillus bulgaricus (used to make yoghurt)
Pneumococcus (causes pneumonia)
What are the characteristics of viruses?
NOT LIVING
Can only reproduce inside living cells. It is a parasite
Infect all types of organisms
Do not have a cellular structure -> they have a protein coat around some genetic material
Parasite = Depends on another organism to survive
What are some examples of viruses?
HIV
Influenza virus
COVID-19
Tobacco Mosaic Virus (Discolours leaves and prevents them from producing chloroplasts)
What are pathogens?
Organisms that cause disease.
Include some fungi, protoctists, bacteria and viruses (even though not technically living)
What is a catalyst?
A substance that speeds up the rate of reaction without being changed or used up
What does ‘optimum temperature/pH’ mean?
The temperature/pH that that enzyme works best at.
Below the optimum and the reaction is slow. Above the optimum and the enzyme denatures
What is diffusion?
The net movement of particles from an area of high concentration to an area of low concentration
Passive process -> Doesn’t require energy
What is osmosis?
The net movement of water molecules from an area of high concentration to an area of low concentration through a semi-permeable membrane
What is active transport?
The movement of particles against the concentration gradient, from an area of low concentration to an area of high concentration. It requires energy released from respiration
Which 4 factors affect the movement of a substance?
- Surface Area to Volume ratio
- Distance that the substance needs to travel
- Temperature
- Concentration gradient
