human biology
scientific method
definition: a precise set of steps/procedure by scientist to conduct investigation
order of scientific method
'recognition of a problem'
'collection of information related to the problem'
'making a hypothesis'
'testing the hypothesis or a prediction made from it'
'collection of data from the experiment'
'if the hypothesis is supported?'
'make a conclusion'
'new question to be answered'
'if hypothesis is disproved'
hypothesis
usually links 2 variables
must be able to be tested
single idea that can be tested
easier to test simple hypothesis rather than complex
definite statement, not question
experiment design
test one variable at a time
includes a "control" (a fair test)
direct observation and collect of data
repetition
tries to reduce error (error are natural) (mistakes are avoidable)
error: define error: anything effecting the accuracy of results or data collected
types of error
random
systemic
human
simply a mistake
unpredictable errors that can occur in all experiments
they occur because no measurements can be precise perfectly
occur because of the way in which an experiment is designed or due to problems with equipment
tables vs graphs
table
table must have an informative title
data presented in column - IV in the left , DV in the right
each column has a heading that names variable and units in which is measured
graph
include a little that summaries the relationship in variables
label the axes with the names of the variables
indicate the units in which each variables is measured
use a scale with equal intervals of unit on each axis
cells
a cell is defined as the smallest structure perform life's function
cell theory - all living organisms, including humans, are made up up of cell and materials produced by cells, cells are the basic structural and functional units of plants and animals - the building blocks that make up all living organism
why do we need a microscope to view cells?
cells are very small, in 1ml of blood there are 5 million blood cells
compare and contrast cells to a brick being built to a house
they are both being building block to make something, used to build structures
cells have many functions, bricks dont
homeostasis - systems working together to maintain a consistent cellular environment, constant temp and conc.
fluid mosaic - the cell membrane is made of a variety of molecules that are able to change positions and still maintain a surface
differentially permeable - cell membrane allow only certain molecule to pass through
diffusion - the spreading out of particles so they are evenly distributed in available space
cell requirements
cells needs to maintain a constant environment - homeostasis
a cell produces and uses material
it needs to exchange material with its surroundings
respiration - what goes in and out of the cell? - oxygen and glucose in carbon dioxide and water out
fluid mosaic model
fluid molecules that make up a cell membrane are in constant motion
mosaic is composed of many different kinds of molecules
phospholid bilayer
lipid( fat tail with phosphate head attached)
bilayer = z layer
structure of membrane helps functions.
4 functions of a cell barrier
a physical barrier -the membrane separates the cell cytoplasm from the extracellular fluid around the cell. isolation is important because composition of cytoplasm and extracellular fluid are very different
regulation of the passage of materials - the membrane controls the movement of materials into and out of the cells - e.g. entry of ions and nutrients, removal of waste release and secretion
sensitivity - the cell membrane is the first part of a cell affected by any changes in the extracellular fluid. it also has receptors that are sensitive to particular molecules in the environment
support - the interval part of the cell membrane is attached to the microfilaments of the cell cytoplasm, thus giving us support to the whole cell. the are also connections between the membrane of adjacent cells that give support to the whole tissue of which the cells are apart