ATAR Human Biology Unit 3: Intro to Scientific Method

• ATAR Human Biology Unit 3 covers introduction, endocrine, and nervous system objectives and terminology.

Introduction and Scientific Method

• Observation involves using the senses to gather information.
• Prediction involves forecasting future events based on gathered information.
• Inference involves logically interpreting observations to form conclusions.
• A testable hypothesis is a proposed explanation that can be tested through experimentation.
• Independent variables are manipulated, dependent variables are measured, and control variables are kept constant.
• Experimental setups are used to test a hypothesis, while control setups provide a baseline for comparison.
• Conducting an experiment means systematically controlling and manipulating variables to test a hypothesis.
• Uncontrolled variables are factors not kept constant which may affect results.
• Sample size refers to the number of subjects/samples and a large sample size is needed for reliable results.
• Random selection involves randomly assigning participants to experimental groups to minimize bias.
• Experimental bias refers to systematic errors that can influence the results.
• A blind test is when participants are unaware of their treatment, and a double-blind test is when both participants and researchers are unaware.
• Repeating experiments is vital to ensure results are consistent and reliable.
• Biological variation is the natural differences between organisms and experimental error is the inaccuracies during data collection.
• A placebo is an inactive substance used as a control in experiments; the psychosomatic effect is when a person's mind affects their body.
• Validity refers to the accuracy of results, reliability is the consistency, and accuracy is how close results are to the true value.
• Improving validity and reliability involves controlling variables, using accurate instruments, and repeating experiments.
• Quantitative data is numerical, while qualitative data is descriptive.
• Data needs to be accurately recorded in an appropriate table.
• Continuous data can take any value within a range, while discontinuous data can only take specific values.
• Data can be represented by graphs.
• The mean is the average of a group of data.
• Percentage changes show the relative change in data.
• Evidenced based conclusion is supported by collected data.
• An extended investigation involves designing and conducting a detailed experiment.
• Identify weaknesses to improve future investigations.
• Ethics involves moral principles and values in society, and investigations must follow ethical principles.
• Calculations include addition, subtraction, multiplication, and division of quantities.
• Numerical expressions are approximated.
• Fractions can be expressed as percentages and vice versa.
• Ratios can be recognized and used.
• Decimal notation can be transformed to power of ten notation.
• Comprehend and use the symbols/notations, Δ, ≈
• Information translates between graphical, numerical and algebraic forms
• Distinguish between discrete and continuous data and then select appropriate forms, variables and scales for constructing graphs
• Frequency tables and diagrams, pie charts and histograms can all be constructed and interpreted.
• Data sets can be described and compared using mean, median and inter-quartile range.
• The slope of a linear graph can be interpreted.

Endocrine System

• Endocrine glands secrete hormones into bloodstream, while exocrine glands secrete substances into ducts.
• The endocrine system consists of glands that secrete hormones to regulate bodily functions.
• The hypothalamus links the nervous and endocrine systems, influencing the pituitary and other glands.
• Hormones are chemical messengers that affect cell function.
• Protein/amine and steroid hormones act differently on cells to change function/action.
• Enzyme amplification is when a small hormonal signal leads to a large cellular effect.
• Hormone clearance is the removal of hormones.
• A synthetic hormone is a lab-created hormone analogue.
• Hormone concentrations are controlled by negative or positive feedback loops.
• The anterior and posterior pituitary differ in their hormone production and action.
• Target tissue and function of hormones varies.
• Hormones produced in humans vary.
• Metabolism refers to all chemical processes in the body and basal metabolic rate is the energy required to maintain vital functions at rest.
• Thyroxine controls basal metabolic rate.
• Hyperthyroidism is overactive thyroid and hypothyroidism is underactive thyroid.
• Hormones and nerves are modes of action that vary in speed, specificity, nature of message, transport, and persistence of action.

Central and Peripheral Nervous System

• The nervous system allows for communication between the body.
• A neuron is a nerve cell.
• Neurons are made up of parts.
• Sensory, connector and motor neurons have different structures and functions.
• Multipolar, bipolar and unipolar neurons have different structures and functions.
• A neuromuscular junction is where a motor neuron communicates with a muscle fiber.
• Resting membrane potential is achieved through ion distribution across the cell membrane.
• A nerve impulse is generated and propagated through depolarization and repolarization.
• Nerve impulses are conducted differently across unmyelinated vs. myelinated fibers.
• A nerve impulse is transmitted across a synapse.
• Chemicals can either promote or inhibit the transmission of nerve impulses.

Divisions of the Nervous System

• The nervous system includes different interconnected parts.
• The spinal cord relays signals.
• The autonomic and somatic divisions differ in control and function.
• The autonomic nervous system controls involuntary body functions.
• The sympathetic and parasympathetic divisions have opposite effects.
• Sympathetic and parasympathetic stimulation affects body organs.
• Nerve pathways of the somatic and autonomic nervous system differ.
• Fight-or-flight responses enable the body to adapt.

Central Nervous System, Receptors, and Reflex Arc

• The central nervous system mainly consists of the brain and spinal cord.
• The central nervous system is protected by the skull, meninges, and cerebrospinal fluid.
• Parts of the brain (cerebrum, cerebellum, medulla oblongata, hypothalamus, corpus callosum) have different functions.
• The major lobes of the brain are organized.
• The cerebral cortex has three types of area.
• The spinal cord has structure and function.
• Grey and white have varying locations and make up.
• A receptor detects stimuli.
• Thermoreceptors, osmoreceptors, chemoreceptors, touch receptors, and pain receptors all have locations and roles.
• Reflex arcs are used to quickly respond to stimuli, protecting the body.
• A nerve impulse travels through a reflex arc.
• A spinal reflex is involuntary, and an acquired reflex is learned.
• Reflexes have four key properties.

Terminology

• Key terms include hypothesis, inference, observation, independent variable, dependent variable, controlled variable, control group, experimental group, sample size, replication, bias, validity, reliability, placebo, psychosomatic, biological variation, experimental error, random selection, exocrine glands, endocrine glands, hormone, neuron, axon, dendrite, myelin sheath, Schwann cell, Node of Ranvier, neurilemma, sensory neuron, motor neuron, connector neuron, multipolar neuron, bipolar neuron, unipolar neuron, nerve fibre, tracts (ascending and descending), nerve, synapse, neuromuscular junction, nerve impulse, saltatory conduction, refractory period, neurotransmitter, CNS, PNS, ganglia, afferent impulse, efferent impulse, autonomic NS, somatic NS, sympathetic NS, parasympathetic NS, meninges, cerebrospinal fluid, cerebrum, cerebellum, medulla oblongata, hypothalamus, infundibulum, corpus callosum, thermoreceptors, osmoreceptors, synthetic hormone, target cell, enzyme amplification, hormone clearance, metabolism, basal metabolic rate, continuous conduction, resting membrane potential, polarised, depolarised, all-or-none response, action potential, chemoreceptor, pain receptor/nocireceptors, touch receptor, reflex, reflex arc, white matter and grey matter.