Section 1 - The Nature and Variety of Organisms P1 Flashcards
What are the 8 life processes?
Movement
Respiration
Growth Reproduction Excretion Nutrition Sensitive Homeostasis
What is homeostasis?
Control internal conditions like body temperature and blood glucose, so conditions round the cells remain constant.
What is respiration?
Process by which living cells release energy from their food.
What is nutrition?
Obtaining food/nutrients either by eating or making food.
What is movement?
Plants move slowly usually by growing towards light. Animals move faster due to muscle contraction away from predators.
What is excretion?
Removal of waste products.
What is sensitive?
Able to detect changes in the environment and respond accordingly.
What is growth?
Increase in mass/gain more cells and a change in the relative size of body parts.
What is reproduction?
Producing offspring in order for species to survive.
Describe common features of plants:(4)
- have chloroplasts so they can photosynthesise
- cells have cell walls, made of cellulose
- store carbohydrates as starch or sucrose
- multi cellular
Describe common features of animals:(5)
- most have some form of nervous coordination, so they can respond rapidly to changes in their environment
- move around from one place to another
- often store carbohydrate in the form of glycogen
- multi cellular
- cells-no chloroplast, no cell wall
Describe common features of virus:(4)
- have a protein coat around some genetic material
- no cellular structure, particles rather than cells-smaller than bacteria
- only reproduce inside living cells
- they infect all types of living organisms
Describe common features of fungi:(6)
- most feed by saprotrophic nutrition(they secrete extra cellular enzymes into the area outside of their body to dissolve the food, so they can absorb the nutrients)
- cell walls, made of chitin
- store carbohydrates as glycogen
- some are single-celled
- others have a body called mycelium made up of hyphae(hyphae contain lots of nuclei)
- can’t photosynthesise
Describe common features of protoctists:(2)
- single-celled and microscopic
- some have chloroplasts and are similar to plant cells, others are more like animal cells
Describe common features of bacteria:(4)
- most feed off other organisms(both living or dead)
- no nucleus, instead they have a circular chromosome of DNA
- some can photosynthesise
- single-celled and microscopic
What is a pathogen?
A disease causing organism.
What can pathogens be?
{Examples for different living organisms]
Protoctists- plasmodium > malaria
Fungi- yeast > ring worm
Bacteria- pneumococcus > pneumonia
Viruses- HIV > AIDs, influenza virus > flu
What are examples of plants?
Flowering plants:
- maize(cereals)
- herbaceous legumes(peas and beans)
What are examples of animals?
Mammals: -humans Insects -houseflies -mosquitoes
What are examples of fungi?
Yeast (single celled fungus)
Mucor (multi celled, has mycelium and hyphae)
What are examples of protoctists?
Chlorella (plant cell like)
Amoeba (animal cell like, lives in pond water)
What are examples of bacteria?
Lactobacillus bulgaricus (used to make yogurt) Pneumococcus (spherical round shape)
What are examples of viruses?
Influenza virus
Tobacco mosaic virus (tobacco leaves discoloured stopping them from producing chloroplasts)
HIV
Why are viruses not classed as an organism?
Viruses don’t excrete
Viruses don’t grow
Viruses don’t control internal conditions
Out of MR GRENSH only does movement and reproduction
What are the levels of organisation in an organism?
Organelles ➡️ Cells ➡️ Tissues ➡️ Organs ➡️ Organ System
What is a tissue?
A tissue is a group of similar cells that work together to carry out a particular function
What is an organ?
An organ is a group of different tissues that work together to perform a function
What are the two types of cells?
Eukaryotic
Prokaryotic
What are eukaryotic cells?
Eukaryotic cells are more complex
-include all animal and plant cells
What are prokaryotic cells?
Prokaryotic cells are smaller and simpler
-e.g. bacteria
What are the organelles typically found in an animal cell?
Nucleus Cell Membrane Cytoplasm Ribosomes Mitochondria
What are the organelles typically found in an plant cell?
Nucleus Cell Membrane Cytoplasm Ribosomes Mitochondria Chloroplasts Cell Wall Vacuole
Cell membrane?
Controls the movement of substances in and out of the cell
Vacuole?
Stores sap(a solution of water, sugars, ions and other substances) Helps support the cell
Nucleus?
Contains the genetic material that controls the activities of the cell
It is surrounded by its own membrane
Cell wall?
Supports the cell and helps keep its shape
Ridged structure made of cellulose
Chloroplast?
Absorb light to make sugar in photosynthesis.
Contains chlorophyll.
Cytoplasm?
Where the chemical reactions take place.
Gel like substance
Contains enzymes which control these reactions
Ribosomes?
Site of protein synthesis
Mitochondria?
Carry out aerobic respiration to release energy that the cell can use
Respiration transfers the energy the cells need to work
Define Diffusion:
Diffusion is the net movement of particles from an area of high concentration to an area of lower concentration.
What is a passive process? (And what is an example?)
A passive process doesn’t require energy
-e.g. diffusion
What states of matter does diffusion happen in?
liquids and gases
What substances do cell membranes let through?
Small molecules (glucose, amino acids, water, oxygen) -Big molecules like starch and proteins can't fit through
What factors affect the rate of diffusion?
The greater the difference in concentration the faster the rate of diffusion
The higher the temperature cause the particles’ll have more kinetic energy
Larger surface area
Short diffusion distances such as thin exchange surface
What is osmosis?
Osmosis is the net movement of water molecules from a region of high water concentration to a region of low water concentration through a partially permeable membrane.
What is an example of a partially permeable membrane?
A cell membrane
State and Describe the process by which water moves in and out of cells:
Osmosis
- tissue fluid surrounds the cells in the body (water, oxygen, glucose)
- there’s normally a different concentration in the tissue fluid than the cells
- if a cell is short of water, so its concentrated, water will move into the cell by osmosis (opposite if a cell has too much water)
What is a catalyst?
A catalyst is a substance which increases the speed of a reaction without being used up or changed in the reaction.
How do you speed up a reaction other than raising the temperature?
- There’s a limit to how far you can raise the temperature before your cells start getting damaged
- Enzymes reduce the need for high temperatures, we only have enzymes to speed up the rate of reaction(metabolic reaction)
What are enzymes?
Enzymes are proteins, made up of chains of amino acids, chains of folded into unique shapes
What’s a substrate?
A molecule that is changed in a reaction
What’s an active site?
Every enzyme has an active site
An active site is where substrate ions join onto an enzyme
In what way are enzymes specific?
Enzymes only work with specific substrates because of the shape of the active site
What’s a lock and key model?
When it is shown how a substrate fits in an active site to form enzyme/substrate complex and then the enzyme is used again
How does temperature affect an enzyme?
-changing the temperature affects the rate of an enzyme-catalysed reaction
-higher temperature increases the rate of reaction at first(more heat, more energy-means higher collision rates between enzymes and substrates)
-lower temperature-lower collision rate-slower reaction
-if it’s too hot an enzyme will denature so the active site shape doesn’t fit the substrate anymore
Each enzyme has an optimum temperature when the reaction goes fastest
What two ways can you measure the effect of temperature on enzyme activity?
Measure how fast a product appears or how fast a substrate disappears
Measuring the effect of temperature on enzyme activity:
Experiment: How can you measure how fast a product appears?
- You can use the enzyme catalyse which catalyses the breakdown of hydrogen peroxide into water and oxygen
- collect the oxygen in a measuring cylinder and measure how much is given off over a certain amount of time
- run a series of experiments with different temperature water baths at different temperatures to see how temperature affects the reaction
- control variables-enzyme concentration, pH,volume of solution
Measuring the effect of temperature on enzyme activity:
Experiment: How do you measure how fast a substrate disappears?
- enzyme amylase catalyses the breakdown of starch to maltose
- detect starch by using iodine on a spotting tile if starch is present the solution will change from browny-orange to blue-black
- you can time how long it takes for starch to disappear by regularly sampling the starch solution and use the times to compare rates between different tests
- by adjust the water bath temperature you can see how temperature affects the amylase
In what way does pH affect enzymes?
- if the pH is too high or low the pH interferes with the bonds holding the enzymes together and this denatures the enzyme
- all enzymes have an optimum pH
Describe how can you investigate diffusion in a non-living system:
- make some agar jelly with phenolphthalein and dilute NaOH (this will make it pink)
- put some dilute HCl and cubes of agar in a beaker
- if you leave the cubes for a while they will become colourless as the acid diffuses in and neutralises the NaOH
Describe an investigation for how you can investigate osmosis in living things:
- cut up a potato into identical cylinders, and put them in different beakers with different sugar solutions in
- measure the length of the cylinders before, and after 30 mins
- if the potato was in water it will expand, if the potato was in a concentrated solution it would shrink
- you can then plot a graph
Describe an investigation for how you can investigate osmosis in non-living things:
- fix some visking tube over a thistle funnel, then pour some sugar solution in
- put the thistle funnel into a beaker of pure water, measure where the sugar solution comes up to
- leave overnight, measure again, water should be drawn up the tube so the solution in the tube will have risen
What is active transport?
Active transport is the movement of particles against a concentration gradient (from low to high) using energy released during respiration.
What four factors affect the movement of substances?
- surface area to volume ratio
- distance
- temperature
- concentration gradient
How does surface area to volume ratio affect the movement of substances?
-the rate of movement of substances is higher with a larger surface area to volume ratio
(a smaller cube would have a higher rate)
How does distance affect the movement of substances?
-the shorter the distance required for substances to travel the quicker the rate
How does temperature affect the movement of particles?
-as particles get warmer and gain kinetic energy, they move faster so this increases the rate
How does concentration gradient affect the movement of particles?
-substances move faster if there’s a bigger concentration difference
-there are more particles on one side to move across
DOESN’T AFFECT ACTIVE TRANSPORT (concentration gradients don’t affect active transport)
What happens is plant cells are put in a solution of pure water?
The cell contents (the cytoplasm and vacuole) push against the cell wall and the cell becomes turgid.
Fully turgid cells support the stems of non-woody plants.
What happens is plant cells are put in a more concentrated solution?
The cell contents lose water by osmosis. They shrink and pull away from the cell wall. The cell becomes flaccid. It is becoming plasmolysed.
What happens is plant cells are put in a highly concentrated solution?
In a very concentrated solution, the cell undergoes
full plasmolysis as the cells lose more water.
