biology Flashcards
Life processes
Movement, respiration, sensitivity, growth, reproduction, excretion, nutrition.
Movement in animals
Animals move using specialised structures (legs or wings) to help them survive.
Movement in plants
Plants cannot move their whole “body” like animals, but they move parts of themselves (like moving their leaves towards the sun).
Movement in nonliving things
Nonliving things can only move if they are pushed or pulled by something else.
Respiration
A chemical process that turns oxygen and glucose from food into energy.
Respiration is important because
All cells need energy, and living things are made up of cells.
Sensitivity
The ability of an organism to respond to changes in its external or internal environment.
Example of sensitivity
You sense that something is hot, it hurts when you touch it and you respond by quickly moving your hand away.
Proprioception
Knowing where your body parts are.
Electroreception
Sensing electrical stimuli.
Magnetoreception
Sensing magnetic stimuli.
Growth
The irreversible increase of an organism’s size over a given period.
Growth in animals
Most animals grow until they reach a certain size and then stop.
Growth in plants
Most plants continue growing throughout their entire lives.
Reproduction
The production of offspring via sexual or asexual reproduction.
Excretion
The removal of waste created by respiration and photosynthesis (so that it does not harm the organism).
Example of excretion
Carbon dioxide is a waste product of respiration, and too much carbon dioxide in your blood can kill you so it must be removed.
Nutrition
The process of taking in food and converting it into energy and other vital nutrients required for life.
Autotrophic nutrition
Photosynthesis
Heterotrophic nutrition
The organism which cannot produce food on their own and depend on other sources/organisms are called heterotrophs
Human full scientific name
Animalia, chordata, primates, hominidae, homo, (homo) sapiens
Why are humans classified as vertebrates?
They have a backbone, and are chordates.
Chordate
A species which has had a notochord at any stage of its life.
Chordate criteria
Gill slits during embryo stage. A post anal tail.
Why are humans classified as mammals?
They are homeothermic (constant body temperature), have a four chambered heart, have hair on the body, young develop within a uterus, females have glands that secrete milk.
Why are humans classified as primates?
They have forward facing eyes and fingernails instead of claws.
Hierarchy of structural organisation
Chemical level, cellular, tissue, organ, system, organism.
Cells
The basic structural and functional unit of living things.
Tissue
A group of cells with similar size and shape that function together for a common purpose.
4 basic types of tissue in the human body
Epithelium (skin), connective (bone/cartilage), muscle, nervous.
Organ
A structure comprised of two or more tissues that has a definite/specific shape, function and location.
Examples of organs
Heart, brain, liver, pancreas.
Organ system
A group of organs that function/work together i.e. coordinated for a common purpose.
Examples of organ systems
Skeletal, muscular, nervous, circulatory, digestive.
Homeostasis
The maintenance of a constant internal environment (keeping the conditions inside your body the same).
Examples of internal conditions that must be maintained at optimal levels
Blood glucose, blood water, body temperature, blood oxygen, temperature.
Optimal temperature for humans
37.5 degrees celsius. Because it is the optimal temperature for chemical reactions in our cells.
How does our body keep the internal temperature the same?
It must balance the heat lost and the heat gained. It does this by using behavioural and physiological methods.
Examples of behavioural methods
Change clothes, cold drink, reducing activity, seek a cool place.
Examples of physiological methods
Sweating, goosebumps, shivering.
Automatic control systems have
Three parts and messages that travel between them. Receptor > processing centre > effector
Receptor
Detects the change.
Processing centre (modulator/coordinator)
Processes information from the receptor and sends information to the effector.
Message
The message that is sent from the modulator to the effector.
Effector
The part of the body that carries out a response.
Stimulus
The change in the internal environment.
Components of a feedback loop
Stimulus, receptor, modulator, message, effector, response, feedback.
Negative feedback
When the output of a system acts to oppose changes to the input of a system. (A reaction that causes a decrease in function).
Cell requirements
To enable normal functioning, all cells in the human body need to be in a relatively stable environment. Body systems work together to ensure that the cellular environment is kept constant.
The cell membrane is composed of
Mainly lipids and proteins.
Two layers make up the single membrane
Lipid bilayer.
How molecules move through the membrane varies depending on
Their size and if they are organic or inorganic.
Very small molecules can
Pass through the small gaps between the lipids. (E.g. oxygen)
Fat soluble substances can
Diffuse across the membrane by dissolving into the lipid (fat). (E.g. alcohol and steroid hormones).
Proteins are
Embedded throughout the membrane and carry out most of the functions of the membrane.
Integral proteins
Bridge the two sides of the membrane.
Peripheral proteins
Embedded in the outside of the membrane.
Cell membranes are described as being
Semipermeable/selectively permeable
Semipermeable
Allows some ions and molecules to pass through but restrict the movement of other. This is usually based on size.
Passive processes
No energy required, can occur in living and dead cells.
Examples of passive processes.
Diffusion, osmosis, facilitated diffusion.
Active processes.
Requires cell’s energy, only in living cells.
Examples of active processes.
Active transport, cytosis.
Diffusion
The net movement of molecules from an area of high concentration to low concentration.
Diffusion only occurs when
There is a difference in concentration between the two areas (e.g. a concentration gradient)
Osmosis
A special case of diffusion that involves the diffusion of water across a cell membrane.
Water molecules are
Very small and pass through very easily.
Osmosis occurs when
Water moves from an area of high concentration of water to an area of low concentration of water.
Cytosis
An active process in which materials move into or out of the cell enclosed as vesicles.
Vesicles
Bubble like structures consisting of either a solid particle or a liquid droplet enfolded in a piece of the cell membrane.
Cytosis is used for
Large particles that are too large to fit through the pores or protein channels in the cell membrane.
Exocytosis
When the material/particle in a vesicle is moved from inside the cytoplasm to the outside.
Endocytosis
When the material/particle is moved from outside the cell into the cytoplasm.
Phagocytosis
When the material/particle is a solid. (Only performed by specialised cells)
Pinocytosis
When the material/particle is a liquid. (Performed by all cells)
Facilitated diffusion
The passive movement of molecules across the cell membrane with the aid of a membrane protein.
Excretion
The removal of wastes produced by metabolism within cells.
Elimination
The removal of undigested materials from the body.
Faeces is
Elimination (except for bile pigments).
Main organs of excretion
Lungs, sweat glands, alimentary canal, kidneys.
Substances removed by lungs
Carbon dioxide and water.
Substances removed by sweat glands
Water, salt, urea.
Substances removed by alimentary canals
Water and bile pigments.
Substances removed by kidneys
Water, salt, urea.
Major parts of the human excretory system
Kidney, ureters, urinary bladder, urethra, urinary opening.
Main sections of a kidney
Medulla, cortex, pelvis.
Function of kidneys
Filter blood to remove wastes and produces urine.
Function of ureters
Transports urine from the kidney to the bladder.
Function of bladder
Temporary storage of urine and contracts to squeeze urine out of the body.
Function of urethra
Transports urine from the bladder to outside the body.
Cortex
(Outside) Where the filtration occurs.
Medulla
(Middle) Where useful substances are reabsorbed.
Pelvis
(Inside) Where urine collects before travelling down to the bladder.
Parts of a nephron
Glomerulus, glomerular capsule, proximal convoluted tubule, descending limb, loop of Henle, ascending limb, distal convoluted tubule, collecting duct
Major stages of the formation of urine
Glomerular filtration, reabsorption, tubular secretion.
Glomerular filtration
Blood enters the glomerulus via the afferent arteriole. Some of the liquid part of blood is forced into the glomerular capsule. The red and white blood cells and plasma proteins are left behind and leave via the efferent arteriole.
Filtrate
The liquid inside the glomerular capsule.
Reabsorption
The filtrate passes into the proximal convoluted tubule and useful substances are reabsorbed into the peritubular capillaries. The filtrate then passes through the Loop of Henle and the distal convoluted tubule where further reabsorption occurs.
Tubular secretion
Adds substances to the filtrate. Hydrogen and ammonium ions are added to the filtrate so that the blood pH remains stable. The fluid is now called urine and passes into the collecting duct and to the ureter.
Nervous system
A series of tissues and organs that are the prime communication system within the body
Two main divisions of the nervous system
Central nervous system, peripheral nervous system
Central nervous system
At the centre of the nervous system. Consists of the brain and spinal cord.
Role of the central nervous system
Receives information from all over your body, processes the information and then sends out messages telling your body how to respond.
Peripheral nervous system
Made up of the peripheral nerves that connect the central nervous system with the receptors and muscles.
Role of the peripheral nervous system
The nerves carry information to and from the central nervous system.
Synapse
The point at which a nerve impulse passes from one neuron to another.
Basic parts of a motor neuron
Cell body, axons, dendrites.
Cell body
Contains nucleus, cytoplasm, organelles. Carries out essential cell processes that keep the cell alive.
Organelles
Mitochondria, endoplasmic reticulum, ribosomes, golgi apparatus
Dendrites
Short branched extensions from the cell body. Consist of cytoplasm surrounded by cell membrane.
Role of dendrites
Receive impulses from other neurons or receptors, conduct impulses towards the cell body.
Axon
Single, long cylindrical processes extending from the cell body. Ends by dividing into synaptic terminals.
Role of the axon
Transmits nerve impulses away from the cell body, towards other neurons.
Myelin sheath
Made of fat (myelin) and gives axons a white appearance.
Role of myelin sheath
Insulates the axon, protects from damage, increases speed of transmission impulses.
Nodes of ranvier
The gaps in the myelin sheath.
Synaptic terminal
At the end of the axons and dendrites. It’s how they join to other neurons.
Sensory neurons
Nerve cells that are activated by sensory input from the environment. E.g. when you touch a hot surface, the sensory neurons are like omg guys something happaned.
Motor neurons
A specialized type of brain cell called neurons located within the spinal cord and the brain.
Connector neurons
Neurons that connect two brain regions.
