the scientific method

notes & exam questions

BIOLOGY

the study of living things

SCIENTIFIC METHOD

ordered logical approach to solving a problem

process of investigation in which problems are identified and their suggested explanations are tested by carrying out experiments

OBSERVATION

unbiased accurate report of an event

HYPOTHESIS

an educated guess based on observations

DATA

measurements, observations, information gathered from experiments

data collected at the end of the experiment is recorded and analysed

CONCLUSION

summary/explanation of the results of an experiment

THEORY

hypothesis that has been supported by experiments over long periods of time it forms a theory

PRINCIPLE OR LAW

theory that has been shown to be valid under all conditions that can be tested it becomes a principle or law

EXPERIMENT

validity of the hypothesis is tested by carrying out an experiment

VARIABLE

factor that may change in an experiment

CONTROL

used as a comparison

standard against which the actual experiment can be compared

REPLICATE

repeat of an experiment

DOUBLE BLIND

both the investigator and the participant are unaware of the nature of the treatment the participant is receiving

ETHICS

whether conduct is right or wrong

EXAM PAPER QUESTIONS

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Two areas of study incorporated in the area of biology

Botany, Zoology, Ecology

Investigate the effect of the herbal extract on the rate of recovery from the common cold.

Ten friends were chosen. They were divided into two groups. Group A was given a glass of herbal extract. Group B was given water. Rate of recovery monitored over 24 hours.

i) Which was the control group?

ii) Two reasons why method of selecting participants reduces reliability of results

iii) Two ways how experimental design could be improved

i) group B

ii) it was nor random and sample size was too small

iii) longer period of time and double blind testing and same volume in each glass

Necessity of random selection

reduces bias and provides greater reliability

Two features of good experimental design

A control, Large sample size, safe procedure

Where are results of scientific research usually first published

Scientific journal

Why is it important to publish research

For peer review, so that others can learn from it and repeat it, information is widely known

Relationship between hypothesis and experiment

An experiment is carried out to test a hypothesis

What information should be contained in the conclusion of an experiment

if prediction was confirmed or not and if the explanation of the results obtained

How can scientists avoid bias in experiments

by having a large sample size, double blind testing and random selection

How is constant pH maintained

using a pH buffer

How is constant temperature maintained

using a water-bath

How to calculate magnifying power of microscope

multiple the power of the eyepiece by the power of the objective lens

Describe how you alter the amount of light shining on your specimens

Adjust the diaphragm, adjust lamp or mirror

why should brown paper used to test for the presence of fat should be allowed to dry out

to ensure the translucent stain is not just water

Which other food test required the application of heat

Reducing sugar or Benedict's

Two steps that characterize the process of the scientific method

observation, hypothesis, experimentation, conclusion, publication, development of theory

Investigate the effect of the concentration of iodine on the rate of growth of tadpoles. scientist used 100 tadpoles that hatched from the same mother. He used water fro the pond and a stock solution of iodine.

i) why do you think it was important for the tadpoles to come from the same mother?

At the start of investigation, scientist divided tadpoles into four groups of 25, one of which was the control.

ii) why was 25 tadpoles used in each group

iii) how would this experiment have been carried out

iv) two factors kept constant during investigation

i) So they are genetically similar

ii) A large sample size would increase death and illness and to make results more statistically significant

iii) Different concentrations of iodine/ made up using pond water/ 25 tadpoles in each solution/ leave for a time/ record changes in tadpole/ compare against control (no iodine)

One safety precaution taken when carrying out practical investigations

use of safety glasses

How do practical investigations contribute to scientific method

To test a hypothesis

One limitation of the scientific method

The extent of our knowledge, the basis of investigation, our ability to interpret results, accidental discoveries

Scientists investigated the effect of a certain mineral on the growth of wheat.

i) suggest a reason why the seeds used were all taken from one parent plant

The compost in which the wheat plants were grown were sterilized at the start of the investigation

ii) how would have scientists sterilized compost

iii) one reason why it is important to sterilize the compost

iv) why did scientists divide the young wheat plants into two equal groups

v)why were the two groups of plants kept under identical conditions

vi) two conditions the scientists would have kept constant in the investigation

vii) why do scientists repeat investigations several times

i) to minimize genetic variation

ii) by heating the compost

iii) to kill organisms and to prevent contamination

iv) as a control

v) to have one variable

vi) temperature, light, pH

vii) to ensure reliability

As a result of her observation a scientist may formulate a ________. She will then progress her investigation by devising a series of _________ and then carefully analyzing the resulting ________.

Hypothesis, experiments, data

Why is a buffer solution used

maintain a constant pH

Biuret test

test for protein

Would you expect a positive or negative result from the biuret test?

a positive result

How is an enzyme denatured?

Boiling it

Stain used when examining cells using a light microscope

iodine or methylene blue

Cutting a window in the pulmonary artery and aorta. Explain purpose of this step

To expose the semi lunar valve

Continuity of Life

The ability of organisms to exist from one generation to the next

Differentiate between organ and system

Organ - tissues make up organs

System - several organs working together

Differentiate between asexual and sexual

Asexual - identical to parents

Sexual - not identical to parents

Five fundamental responses that organisms show to stay alive

Organisation, Nutrition, Excretion, Reproduction

Name an anabolic reaction

Photosynthesis

Two dissolved salts

magnesium, sodium, chlorine, potassium, calcium

Define organisation

Organisms are grouped from cells into tissues