unit 2 out 2 Flashcards
adaption
an inherited characteristic that increases the likelihood of survival and reproduction in the face of changing conditions.
adaptions are the result of the evolutionary process of Natural Selection, in which those organisms that are best suited to their environment survive and reproduce, passing on their advantageous adaptions of their offspring.
abiotic factors
challenges to adaption and survival
non-living components of an environment, such as water, temperature, pH and salinity
Biotic factors
challenges to adaption and survival
living components of an environment such as bacteria, fungi, plants and animals.
broad categories of challenges to adaption and survival.
- structural (morphological or anatomical)
- physiological (functional)
- behavioral
structural adaptions
ANIMAL
e.g. thick layer of fat to insulate an animal that lives in the cold
- bright feathers to help attract mates
- large ears to increase heat loss
- webbed feet and flippers for swimming
- spines for protection against predators
- patterned body coverings for camouflage
PLANT
e.g. plants in hot or windy environments conserve water by having:
- reduced leaf surface area
- fewer stomata
- stomatal hairs that create a humid microclimate
- sunken stomata
- rolled leaves
- leaves oriented away from the sun.
pneumatophores
aerial roots
adaptions to water-logged environments which allow roots to take up oxygen.
physiological adaptions
internal or external
shivering (muscles) when it is cold
Kangaroo reabsorbing embryo when conditions are harsh
bacteria evolving to eat unusual food sources (e.g. nylon)
increased RBC (red blood cells) in high altitude.
- are internal changes
common octopus
- colour-changing cells called chromatophores enable it to change colour to match its surroundings
- physiological mechanisms move pigment to and from the cells and change their reflection to produce the effect.
CAM plants
Found in dry environments
Stomata open only at night to collect carbon dioxide, which is stored as malic acid in cell vacuoles
During the day malic acid is converted back to carbon dioxide for photosynthesis
Enables plant to close stomata during the heat of the day to reduce water loss
Countercurrent Heat Exchange
Seal fins, the legs of artic birds, platypus feet and tuna muscle
Heat is held deep within the animal and not carried to the body surface where it would be lost to the environment.
topor: where metabolic rate is lowered to save energy, enabling organism to cope with cold, heat, or decreased food availability:
- hibernation in mammals and birds, where body temperature and heart rate is decreased.
adaptions for movement in plants
tropism is plant growth in response to an environmental factor:
- phototropism: growth in response to light
- geotropism or gravitropism: growth in response to gravity
- chemotropism: growth in response to chemicals
- thigmotropism: growth in response to touch
- hydrotropism: growth in response to water concentration
nastic movement
Thigmonastry: movement in response to touch e.g. venus fly trap obtains nitrogen by trapping prey such as flys
Photonasty: movement in response to a change in light intensity. e.g. flowers and leaves opening during day and closing at night.
Thermonasty: movement in response to a change in temperature e.g. tulip flowers open in response to air temperature.
behavioral adaptions
e.g. migration group social structures seeking or leaving shade or shelter evaporate cooling to lower body temperature huddling to maintain body temperature
biomimicry
an approach to the innovation and design of products modeled on structures and systems found in nature. can be either:
- form level, e.g. Velcro
- process level, e.g. engineering algorithms based on the behavior of ants and bees.
- systems level, e.g. increased efficiency of wind turbines based on movement of whale flippers in water.
homeostasis
the maintenance of the internal environment in a relatively stable state in the face of changes in either the external or internal environment.
carried out by endocrine and nervous systems in animals.
stimulus-response model
stimulus: an environmental factor that an organism can detect and respond to (excites or stimulates a receptor)
internal factors: chemical - O2, CO2, glucose, ions, H2O, wastes. physical - temperature, balance, blood pressure.
external factors: chemical - food, O2, CO2, H2O and specific chemicals. physical - light, temperature, gravity, sound, day length.
receptors: specialised structures capable of responding to specific stimuli. produce a signal (either electrical or chemical)
- mechanoreceptors: pressure, tension
- chemoreceptores: chemicals (taste, smell)
- photoreceptors: light
- thermoreceptors: temperature
- other: pain, touch
control centre: receives the message, determines action by the effector
- often the brain
- in reflex arcs it is the spinal cord.
effector: cells, tissues, muscles or glands which respond to the message/stimulus
response: action brought about due to initial stimulus.
negative feedback
Produce stability act to restore the original state
Are stimulus-response models in which the response reduces the original stimulus (negative effect)
Regulation involves fluctuations around a set point
positive feedback
Mechanism in which the disturbance causes a change that increases the initial disturbance
Decrease stability
Do not occur very often in biological systems
human endocrine system
system for hormones
Hormone: a chemical messenger that causes a cellular response
three types: peptide hormone, protein or amino acid derived hormone, steroid hormone (synthesised from cholsterol)
- secreted directly into the bloodstream thus can trigger a specific cellular reaction in target tissues and organs some distance away
- produced by specialised cells/glands called endocrine glands
- endocrine system generally regulates activities that require duration rather than speed
e.g. water and electrolyte balance, stress, growth and development, reproduction
steroid vs protein hormones
Steroid hormones are lipid soluble and pass through the cell membrane where they bind to their specific receptor.
Protein hormones are water soluble and cannot pass through the cell membrane. they bind on the outside of the cell membrane and trigger physiological responses within the cell
nervous system
the rapid response characteristic of most animals is brought about by the nervous system nervous system consists of: - brain - spinal cord - nerves
central nervous system (cns)
brain and spinal cord
parts of the brain
hypothalamus: controls the automatic nervous system, regulates the release of hormones and is involved in temperature, water balance and blood pressure
pituitary gland: maintains and control of the endocrine system
peripheral nervous system (pns)
connects the CNS to other parts of the body, and is composed of nerves (bundles of neurons
PNS divided into: somatic and autonomic
sensory neurons
running from stimulus receptors that inform the CNS of the stimuli
motor neurons
running from the CNS to the muscles and glands
somatic nervous system
conscious control
uses input from sense organs
controls motor functions
transmits messages to skeletal (voluntary) muscles, tendons and skin
autonomic nervous system
involuntary function uses input from internal receptors controls visceral (internal organs in the chest) functions can be divided up into the sympathetic (fight or flight responses) and parasympathetic nervous system (relaxing responses)
nerve cells
neurons (or nerve cells) consist of a cell body, dendrites, and a long axon
neurons conduct electrical impulses
nerves are made up of a bundle of neurons
schwanns cells
apart of myelin sheath
cell inside
transmission of nerve impulses
the signal transmitted by a nerve is an electrical impulse
the nerve impulse is known as an action potential
the nerve impulses propagate only in one direction
reflex arc
a reflex arc is the simplest circuit of neuron
does not involve the brain, but synapse in the spinal cord
this characteristic allows reflex actions to occur relatively quickly by activating spinal motor neurons without the delay of routing signals through the brain, although the brain will receive sensory input while the reflex action occurs
e.g. pain withdrawal, or a knee jerk response
chemical transmission
chemical transmission occurs at synapse
neurotransmitters
comparison of hormone and nervous system
NERVOUS SYSTEM:
- speed of travel: rapid (fractions of a second)
- method of transmission: action potential along nerves (electrical), chemical transmission across synapses
- target: specific destination, e.g. muscle, gland
- duration of response: immediate, short lived
HORMONAL SYSTEM:
- speed of travel: slow - seconds, minutes
- method of transmission: chemical substance (messages) released into circulatory system to all parts of the body, may travel long distances
- target: widespread distribution but target is specific to the hormone, a particular hormone may affect cells in several target organs
- duration of response: temporary (few seconds or minutes), e.g. adrenaline - long lasting, e.g. pituitary hormones affecting growth and mental ability over years