The nature and variety of organisms Flashcards
(22 cards)
What are the characteristics of organisms? (Clue MRS H GREN)
MOVEMENT
RESPIRATION
SENSITIVITY
GROWTH
REPRODUCE
EXCRETE
NUTRITION
Homeostasis = Control their internal conditions in a tight range.
Describe the Levels of Organisation in Organisms:
Then describe one of the levels:
Organelles - cells - tissues - organs - organ systems - organism.
( To describe one you need to say a group of similar/different … working together for one function)
Describe the cell structure of an animal cell:
- Nucleus
- Cell membrane
- cytoplasm
- Mitochondria
- Ribosomes
Nucleus: organelle which contains the genetic material that controls cell activities.
Cell Membrane: Forms the outer surface of the cell and controls the substances going in and out.
Cytoplasm: gel like substance where most chemical reactions happen. Contains enzymes.
Mitochondria: Small organelles where most of the reactions for aerobic reaction takes place.
Ribosomes: Small organelles where proteins are made.
Explain the Extra cell structures of a plant cell:
- Chloroplasts
- Cell wall
- Vacuole
Chloroplasts: photosynthesis (makes food for the plant) and contains chlorophyll.
Cell wall: Rigid structure made of cellulose which supports and strengthens the cell.
Vacuole: large organelle that contains cell sap and provides supports for the cell.
Explain specialised cells and give two examples of specialised cells:
Cells are specialised to carry out a particular function so their structures can vary. e.g. red blood cells and white blood cells.
Explain Embryonic stem cells:
- They are cells that are found in early human embryos that are undifferentiated and can produce lots of other stem cells by dividing.
- They can differentiate into different types of cells depending on the instructions they have been given.
- They can be found in adult bone marrow as well.
a) How could stem cells be able to cure many diseases?
b) What are Some risks of stem cells in medicine?
- Bone marrow from a healthy person can replace the faulty blood cells in another patient.
- Embryonic stem cells could be used to replace faulty cells in sick people.
RISKS: - Stem cells grown in a lab may have been contaminated with a virus and could be passed onto a patient and make them even sicker.
What are the ethical issues involving stem cell research? (Include for and against).
AGAINST:
- They feel that human embryos shouldn’t be used since each one is a human life or has the potential to be a human life.
- Scientists should be finding and developing other sources of stem cells.
FOR:
- Curing patients who are suffering is more important than the rights of embryos.
- They say that the embryos are unwanted from a fertility clinic which if weren’t being used for research would be destroyed.
a) What are the features of plants?
b) What group are they in?
- Are multicellular
- Have chloroplasts so can photosynthesise
- Have a cellulose cell wall
- store carbohydrates as sucrose or starch
b) are eukaryotic organisms
a) What are the features of Animals?
b) What group are they in?
- Are multicellular
- No chloroplasts, cant photosynthesise
- No cell walls
- nervous coordination (can quickly respond to changes in the environment)
- store carbohydrates as glycogen
b) are eukaryotic organisms
a) What are the features of Fungi?
b) What group are they in?
- Some are single celled
- Others have a mycellium body made up of hyphae (contain nuclei+thread like structures)
- Cant photosynthesise
- Chitin cell walls
- Feed by saprotrophic nutrition ( excrete enzymes then adsorb nutrients)
- store carbohydrates as glycogen
b) are eukaryotic organisms
a) What are the features of protoctists?
b) What group are they in?
- Single celled and microscopic
- some have chloroplasts and more similar to plant cells
- Others are more similar to animal cells
a) What are the features of Bacteria?
b) What group are they in?
- Single celled and microscopic
- no nucleus
- circular chromosomes of DNA
- Some can photosynthesise
- Most feed off other organisms living and dead.
a) What are the features of Viruses?
b) What group are they in?
- particals not cells (smaller than bacteria)
- reproduce inside living cells (parasite)
- Infect all types of living organisms
- loads of different shapes and sizes
- Don’t have a cellular structure - they have a protein coat and some genetic material.
What is the meaning of a Pathogen?
A disease causing organism:
e.g.
PROTOCTIST: plasmodium , malaria
BACTERIUM: Pneumococcus , pneumonia
VIRUSES: Influenza virus , Flu
What can affect the rate of reaction?
- Increased temperature (more energy, more collisions) however too much can cause the enzyme to denature.
- PH (interferes with bonds.
The optimum temperature is when the enzyme works best.
Why are enzymes very specific?
1) Chemical reactions involve things being split apart or joined together.
2) Every enzyme molecule has an active site where a substrate joins to the enzyme.
3) A substrate has to have a specific shape to fit the active site.
4) This is an example of the lock and key analogy.
What is diffusion?
a) meaning
b) example
a) The net movement of particals from a high concentration to a low concentration. It is a passive process and happens in liquids and gases.
b) When perfume diffuses through a room.
How do cell membranes work?
- They hold the cell together but also let stuff in and out of the cell.
- Substances move in and out of cells by diffusion, osmosis and active transport.
- Only some molecules can fit through the membrane e.g water, oxygen and amino acids however starch and protein can’t fit.
What is osmosis?
Osmosis is the net movement of water molecules across a partially permeable membrane from a region of high water concentration to a region of low water concentration.
What is active transport?
Active transport is the movement of particals against a concentration gradient using energy released during respiration.
What factors affect the movement of substances? Name four.
1) Surface area to volume ratio.
2) Distance to move.
3) Temperature.
4) concentration gradient.
