AQA Biology Unit 2 Foundation Part 1
A bunch of revision cards for Biology AQA Unit 2 Foundation. Part 1 is Cells, Organs and Populations
- Created by: Lewis Jones
- Created on: 07-05-13 16:37
Cells
Cells
Bacterial Cell
- No Nucleus
- DNA floats in cytoplasm because of no nucleus
Cells
Yeast
- Only one cell
Diffusion
- Slow movement of particles from a place where there are lots of particles to places where there are fewer of them
- Diffusion is the spreading out of particles from an area of high concentratrion to an area of low concentration
Cell Membranes
- Hold cell together.
- Also allow stuff in and out the cell
- Very small molecules like Oxygen, Glucose and Amino Acids can fit through cell membranes
- Big molecules like Starch and Proteins can't fit through
- Dissolved substances can move in and out the cell by diffusion
- Molecules move from high concentration (alot of them) to low concentation (Not alot of them)
- They move boths ways. May have net movement if there are too many molecules on one side
Specialised Cells
- Do a Specific Function
- For an example, Palisade leaf cells carry out Photosynthesis so it will need lots of Chlorplast
Differentiate to Specialised
( O ) --------------------> ( oo OOO oo)
Unspecialised Cell Differentiation Specialised cell (new features)
- This is called Differentiation
- Occurs when multicellur organisms (Humans and plants) develops (grow)
- Specialised cells form tissues, which forms organs, which forms organ systems
Tissues
- Group of specialised cells that have a similar structure and function to do a specific function/job
- e.g. Muscular tissues, Glandular tissues and Epithelial tissues
Organs
- A group of different tissues that work together to perform a certain function
- A stomach organ is made up of these tissues:
- Muscular tissue, Moves stomach wall to churn (mix) up the food
- Glandular tissue, Makes diggestive juices to digest food
- Epithelial tissue, Covers outside and inside the stomach
Epithelial tissue - Less than 0.1mm
Stomach - About 10cm
Organ Systems
- Group of organs working together to perform a paticular function
- The body has several organ systems such as:
- The nervous system
- The respiratory system
- The reproductive system
- The digestive system
How plants use Glucose
- For Respiration
- Making Cell Walls (Cellulose)
- Making Proteins
- Stored in Seeds
- Stored for Starch
Distribution of Organism
- The distribution of an organism is where an organism is found
- Environment varies
- Environmental factors: Temperature, Amount of water, Amount of light, How much oxygen there is, How much Carbon Dioxide there is and if there is enough food around
- An organism might be more common in one area than another due to environmental factors. e.g. you will find more daisies on the open field than under tree's due to sunlight
- We use Quadrats or Transects to find the distrubution of organism
Quadrats
- These are used to see how common an organism is in two different areas (sample areas)
How to do it?
1) Place a 1m² Quadrat at a randon point within the first sample area
2) Count all the organisms within the Quadrat
3) Repeat step 1 and 2 as many times as you can
4) Work out the mean (average) number of organisms within the first sample area.
Mean = Total number of organism / Number of Quadrats
Median = The middle value when results are put in order of size
Mode = Most common
6) Repeat step 1 and 4 in the 2nd sample area
7) Finally compare the 2 means
Transects
- Transects are another way of finding out the distribution of organism across an area. These use lines.
How to do it?
1) Mark out a ling in the area you want to study using a tape measure
2) Collect data along the line by:
- Counting all the organisms that touch the line (Left side on the picture)
- Using Quadrats placed along the line (Right side on the picture)
Population Size
Population size = Mean number of organism per 1m² quadrat x Total area (in m²)
For an example, There are 7 daisies per m² in a 100cm² field. So the population size = 7 x 10 = 700 daises
Collecting Environmental data
Realiability
Are the results realiable?
Are your results repeatable and reproducible?
To make results more reliable you need to: take a large sample size (lots of quadrats) or/and use random samples (Different areas)
Validity
Must be reliable to be valid
To answer original question you need to control all variables.
Question: Whether a difference in distribution between sample areas is due to a difference in one environmental factor
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