1 - Structures and Functions in Living Organisms Flashcards
What are the characteristics of all living organisms?
M - move R - respiration S - sensitivity C - control G - growth R - reproduction E - excreting N - nutrition
What is in an animal cell?
Nucleus
Cell membrane
Cytoplasm
What is in a plant cell?
Nucleus Cytoplasm Cell membrane Cell Wall Vacuole Chloroplasts
What is the function of a nucleus?
An organelle which contains the genetic material that controls the cell’s activity. Surrounded by its own membrane
What is the function of a cell membrane?
Forms the outer surface of the cell and controls what goes in and out
What is the function of cytoplasm?
A gel-like substance where most of the cell’s chemical reactions happen. Contains enzymes which control these reactions
What is the function of chloroplasts?
Contains a green substance called chlorophyll which enables photosynthesis
What is the function of a cell wall?
A rigid structure made of cellulose which surrounds the cell membrane. Supports and strengthens the cell
What is the function of a vacuole?
A large organelle that contains cell sap (a weak solution of sugars and salts). Also helps to support the cell
What is the function of cells?
They are specialised to carry out a particular function and their shape, size and strength can vary (e.g.. red blood cells carry oxygen)
What are tissues?
A group of similar cells that work together to carry out a particular function. Can contain more than one cell type (e.g. xylem tissues carry water in plants)
What are organs?
A group of different tissues that work together to perform a function (e.g. lungs in mammals)
What are organ systems?
Organs work together to form organ systems. Each system does a different job (e.g. in mammals the digestion system is made up of organs such as the stomach and intestines)
What are typical plant features?
- Multicellular
- Contain chloroplasts for photosynthesis
- Have cell walls made of cellulose
- Store carbohydrates as sucrose or starch
What are examples of plants?
- Cereals (e.g. maize)
- Herbaceous legumes (e.g. peas and beans)
What are typical animal features?
- Multicellular
- No chloroplasts
- No cell walls
- Most have some kind of nervous coordination meaning they can respond rapidly to changes in their environment
- Can move from one place to another
- Store carbohydrates in the form of glycogen
What are examples of animals?
- Mammals (e.g. humans)
- Insects (e.g. houseflies or mosquitos)
What are typical fungi features?
- Some are single-celled
- Others have a body called a mycelium which is made from hyphae that contains lots of nuclei
- Cannot photosynthesise
- Cell walls made of chitin
- Feed by saprotrophic nutrition
- Store carbohydrates as glycogen
What are examples of fungi?
- Yeast (single-celled fungi)
- Mucor (multicellular and has a mycelium and hyphae
What is saprotrophic nutrition?
When an organism secretes extracellular enzymes into the area outside their body to dissolve their food so they can then absorb the nutrients. Fungi sometimes feed this way.
What are typical protoctists features?
- Single-celled
- Microscopic
- Some have chloroplasts and are similar to animal cells
- Look like a fish with string as a tail
What are examples of protoctists?
- Chlorella (plant-cell-like)
- Amoeba (animal-cell-like and lives in pond water)
What are typical bacteria features?
- Single-celled
- Microscopic
- No nucleus
- Circular chromosome of DNA
- Some can photosynthesise
- Feed off other organisms (both living and dead)
- Look like a sideways plant cell with a ‘dog’ DNA strand
What are examples of bacteria?
- Lactobacillus bulgaricus (used to make milk go sour and turn into yoghurt, rod shaped)
- Pneumococcus (round in shape)
What are typical virus features?
- Particles, rather than cells
- Smaller than bacteria
- Parasite (can only reproduce inside living cells)
- Infect all types of living organisms
- Come in loads of shapes and sizes
- no cellular structure (protein coat around some DNA or RNA)
- Hexagon with protein squiggle inside
What are examples of viruses?
- Influenza virus
- HIV
- Tobacco mosaic virus (makes the leaves in tobacco plants discoloured by stopping chloroplasts being produced)
What are pathogens?
Organisms that cause a disease. Can include some fungi, protoctists, bacteria and viruses
What are examples of pathogens?
Protoctists - Plasmodium (causes malaria)
Bacterium - Pneumococcus (causes pneumonia)
Viruses - influenze virus (causes flu) and HIV (which causes AIDS)
What are enzymes?
A biological catalysts - speeds up all the reactions in the body.
It is a protein (made of amino acids) and is specific meaning it will only catalyse one type of reaction.
Optimum temperature is 37*C - above this is becomes denatured
What is a substrate?
A molecule that has been changed in a reaction
What is an active site?
The place where a substrate joins the enzyme
Describe an experiment to measure the rate of production depending on the temperature of the enzymes
- The enzyme catalase catalyses the breakdown of hydrogen peroxide into water and oxygen
- Collect the oxygen produced in a gas tube in a set amount of time (using a stop watch) e.g. a minute
- Put the test tube in a water bath and change the temperature to measure different effects
- Control the variables (e.g. enzyme concerntration, pH, colume of solution)
Describe an experiment to measure how quickly a substrate disappears depending on the temperature of the enzymes
- The enzyme amylase catalyses the breakdown of starch to maltose
- Use iodine (if starch is present it will turn from browny-orange to blue-black)
- Time how long it takes for the starch to disappear by regularly sampling the starch solution
- Adjust the temperature in the water bath to see how it affects the time
What pH are enzymes?
- Often neutral (7)
- Pepsin needs pH2
What is diffusion?
The movement of molecules from a high concentration to a low concentration
Happens in liquids and gases
What is osmosis?
The movement of water molecules froma high concentration to a low concentration through a semi-permeable membrane
e.g. in a water solution and sucrose solution the water molecules will move from the water to the sucrose solution
What is a turgid cell?
When a plant cell is well watered and all its cells are plump and swollen
The pressure of the water against the cell wall is called the turgid pressure and helps to support the plant tissue
If a plant cell isn’t turgid the plant will droop and wilt
Describe an experiment for diffusion
- Make some agar jelly with phenolphthalein and dilute sodium hydroxide solution (this makes the jelly pink)
- Fill a beaker with HCl and put a few cubes of the jelly in the beaker
- The jelly will turn from pink to colourless
Describe an experiment for osmosis in a living system
- Cut up a potato into identical cylinders
- Fill a few beakers with different sugar solutions (one should be pure water)
- Measure the lengths of the cylinders
- Leave for a half hour
- Measure them again
- If osmosis was drawn in they will be taller
- If osmosis was drawn out they will have shrunk
Describe an experiment for osmosis in a non-living system
- Tie a piece of wire around one end of some Visking tubing and put a glass tube in the other end (fixing the tubing around it with wire
- Pour some sugar solution down the glass tube onto the Visking tubing
- Put the Visking tubing in a beaker of pure water (measure where the sugars solution comes up to on the glass tube)
- Leave the tubing overnight then measure where the liquid is in the glass tube
- The water should be drawn into the Visking tubing by osmosis and this will force the liquid up the glass tube
What is active transport?
The movement of particles against a concentration gradient - from a lower concentration to a higher concentration - using energy release during respiration
What are factors affecting the movement of substances?
- Temperature
- Concentration (bigger difference = faster)
- Surface area to volume ratio (higher different = faster)
What do ribosomes do?
Make proteins from amino acids according to instructions from the DNA
What does the mitochondria do?
Release energy by aerobic respiration
How do plants store food?
As starch
