unit 2 out 2

Question 1

adaption

Answer 1

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.

Question 2

abiotic factors

Answer 2

challenges to adaption and survival

non-living components of an environment, such as water, temperature, pH and salinity

Question 3

Biotic factors

Answer 3

challenges to adaption and survival

living components of an environment such as bacteria, fungi, plants and animals.

Question 4

broad categories of challenges to adaption and survival.

Answer 4

• structural (morphological or anatomical)
• physiological (functional)
• behavioral

Question 5

structural adaptions

Answer 5

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.

Question 6

pneumatophores

Answer 6

aerial roots

adaptions to water-logged environments which allow roots to take up oxygen.

Question 7

physiological adaptions

Answer 7

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

Question 8

common octopus

Answer 8

• 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.

Question 9

CAM plants

Answer 9

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

Question 10

Countercurrent Heat Exchange

Answer 10

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.

Question 11

adaptions for movement in plants

Answer 11

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

Question 12

nastic movement

Answer 12

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.

Question 13

behavioral adaptions

Answer 13

e.g. migration
group social structures
seeking or leaving shade or shelter
evaporate cooling to lower body temperature
huddling to maintain body temperature

Question 14

biomimicry

Answer 14

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.

Question 15

homeostasis

Answer 15

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.

Question 16

stimulus-response model

Answer 16

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.

Question 17

negative feedback

Answer 17

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

Question 18

positive feedback

Answer 18

Mechanism in which the disturbance causes a change that increases the initial disturbance
Decrease stability
Do not occur very often in biological systems

Question 19

human endocrine system

Answer 19

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

Question 20

steroid vs protein hormones

Answer 20

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

Question 21

nervous system

Answer 21

the rapid response characteristic of most animals is brought about by the nervous system
nervous system consists of:
- brain
- spinal cord
- nerves

Question 22

central nervous system (cns)

Answer 22

brain and spinal cord

Question 23

parts of the brain

Answer 23

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

Question 24

peripheral nervous system (pns)

Answer 24

connects the CNS to other parts of the body, and is composed of nerves (bundles of neurons
PNS divided into: somatic and autonomic

Question 25

sensory neurons

Answer 25

running from stimulus receptors that inform the CNS of the stimuli

Question 26

motor neurons

Answer 26

running from the CNS to the muscles and glands

Question 27

somatic nervous system

Answer 27

conscious control uses input from sense organs controls motor functions transmits messages to skeletal (voluntary) muscles, tendons and skin

Question 28

autonomic nervous system

Answer 28

``` 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) ```

Question 29

nerve cells

Answer 29

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

Question 30

schwanns cells

Answer 30

apart of myelin sheath | cell inside

Question 31

transmission of nerve impulses

Answer 31

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

Question 32

reflex arc

Answer 32

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

Question 33

chemical transmission

Answer 33

chemical transmission occurs at synapse | neurotransmitters

Question 34

comparison of hormone and nervous system

Answer 34

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

Question 35

plant hormones

Answer 35

although plants do not have a nervous system, they are able to detect environmental signals and use hormones to transfer a message to those parts where a response is needed. - growth response is response to an external stimulus are called tropisms - growth towards the stimulus is a positive tropism, e.g. positive phototropism involves growth towards the light - growth away from the stimulus is a negative tropism hormones is plants are responsible for: - apical dominance: inhibition of lateral branches - ripening of fruit: conversion of starches to sugars - abscission: shedding of leaves and flowers

Question 36

auxin - hormone

Answer 36

where produced: shoot tip (meristem) effective site: growing region of shoot action: cells elongated under turgor pressure visible effect: tip bends towards light; apical dominance; used as herbicides; stimulates cuttings to root

Question 37

phototropism

Answer 37

is the bending and growing of plants towards a source of light, to maximise photosynthesis caused by the hormone Auxin which is produced in the growing tip

Question 38

geotropism

Answer 38

Auxin produced is root tips is also involved in promotion of root tip in response to gravity

Question 39

homeostatic mechanisms

Answer 39

temperature (thermoregulation) blood glucose water balance (osmoregulation)

Question 40

humans are endotherms

Answer 40

- temperature sensitive cells in the hypothalamus act as misalignment detectors which detect blood temperature deviating from a set point. - skin temperature receptors act as disturbance detectors and trigger a response before there is a change in core body temperature.

Question 41

heat loss

Answer 41

conduction: transfer of heat energy from a hotter object to a cooler object with which it is in contact, e.g. touching ice convection: transfer of heat by means of warmed air or water, rising and being replaced bey cooler air or water radiation: transfer of heat from a hot object to the atmosphere by means of infra-red waves evaporation: liquid to gas, requires heat

Question 42

source of body heat

Answer 42

ectotherms: rely on the external environment for heat, e.g. snake endotherms: produce heat through their metabolism, e.g. humans, other mammals

Question 43

temperature difference

Answer 43

the steeper the gradient the more rapid the heat gain or loss

Question 44

responding to cold

Answer 44

- vasoconstriction (constriction of blood vessels in the skin) - reduces heat loss from the skin as the amount of blood moving close to the exposed surface is reduced - piloerection (goose bumps). the contraction of blood vessels and small muscles pull the hair into an upright position, trapping a layer air - in animals with thick fur this reduces heat loss from the body, but on mammals it has minimal effect - seeking shelter - decreasing surface area - curling up - putting on more clothes - voluntary movement - shivering thermogenesis: this voluntary movement of the muscles generates large amounts of heat, stimulated by adrenaline - non-shivering thermogenesis: increased cellular activity in brown fat (brown adipose tissue or BAT) which is tissue specialised for heat production - thyrotropin releasing hormone (TRH) is secreted by the hypothalamus. TRH acts on the anterior pituitary to secrete Thyroid stimulating hormone (TSH). TSH acts on the thyroid gland to release T3 and T4 hormones which increase cellular respiration

Question 45

responding to heat

Answer 45

- sweat is produced by sweat glands - body heat is used to evaporate sweat from skin - changing state from liquid to gas uses heat energy and thus cools the surface of the skin - vasodialtion of blood vessels - increased blood flow to surface which increases heat loss - slowing the rate of cellular respiration in internal organs e.g. by decreasing activity - moving out of sun into shade - changing body shape to increase surface area, e.g. by standing with arms and legs out stretched - increase exposure to wind - wind pushes heat away from skin, increasing temperature gradient

Question 46

control of blood glucose level

Answer 46

Glucose is stored as glycogen in liver When blood glucose levels fall (e.g. when a person hasn't eaten for a while), the body breaks down glycogen into glucose for cellular respiration When blood glucose levels rise (e.g. after food) the body stores glucose as glycogen. When blood glucose levels deviate from the acceptable range, cells in the pancreas called the islets of Langerhans respond by releasing hormones; either insulin (which stores glucose), or glycogen (which releases it)

Question 47

osmoregulation

Answer 47

- maintaining water balance is necessary to control salt concentrations - salts from ions in solution and cells require concentrations of ions to be within narrow limits of efficiency of biochemical processes. - if we consume a lot of water, there will be too much water in the blood, the kidneys will then produce a lot of very dilute urine to get rid of the extra. - if the body is short of water, the kidneys will produce only a very small amount of more concentrated urine - osmoreceptors in the hypothalamus are sensitive to blood solute concentrations - baroreceptors in the atria of the heart detect changes in blood pressure - within the body, water moves by osmosis across semi-permeable membranes from areas of higher free water molecules to areas of lower free water molecules.

Question 48

regulation of water

Answer 48

negative feedback mechanism - control of amount of Anti-diuretic Hormone (ADH) produced.

Question 49

factors inhibiting ADH release:

Answer 49

high water concentration in blood low salt concentration in blood alcohol

Question 50

result of low ADH

Answer 50

decrease water reabsorption | urine output increases

Question 51

factors causing ADH release

Answer 51

low salt concentration in blood | high salt concentration in blood

Question 52

result of high ADH

Answer 52

water reabsorption increases | urine output decreases

Question 53

malfunctions in homeostatic mechansims

Answer 53

diseases in the endocrine system fall into 3 groups: - hypersecretion (oversupply of hormones) - hyposecretion (undersupply of hormones) - cancers of endocrine glands

Question 54

hyperthyroidism

Answer 54

the thyroid gland secretes important hormones that are responsible for regulating growth, development and metabolic rate. - excess amounts of triiodothyronine (T3) and tyroxine (T4) hormones are secreted - this provides a negative feedback message to the hypothalamus to decrease the release of thyrotropin releasing hormone (TRH) and thyroid stimulating hormone (TSH).

Question 55

causes and symptoms of hyperthyroidism

Answer 55

there are many causes, including Graves' disease which is an autoimmune condition symptoms can include development of an enlarged thyroid called a goitre there are a wide range of symptoms

Question 56

management of hyperthyroidism

Answer 56

drugs called beta-blockers which slow down increased heartbeats and tremors anti-thyroid drugs radioactive iodine treatment surgery - removal of all or part of the thyroid

Question 57

how do organisms interact within the environment

Answer 57

All organisms affect and are affected by their surroundings These interactions can be with - abiotic factors: e.g. plants taking in CO2 - biotic factors: e.g. a cow eating grass in a paddock Humans are the only species that changes environments to suit themselves This means that we affect the environments around us Understanding environments is essential to allow us to minimise harm where possible or to restore damaged areas

Question 58

organising the environment

Answer 58

Environments can be studied on many levels from an individual, population or ecosystem to the whole planet. 1. individual level: single individual of a species, such as plant, animal, fungi or unicellular organism 2. population level: a group of organisms of the same species living in a defined geographic area 3. community level: ecological grouping of different kinds of organisms in a specific place and time that interact with each other 4. ecosystem level: a system formed by organism interacting with one another and their physical environment, can be small scale, such as a dead tree or large scale, such as a large forests. can be : - simple - such as a desert - complicated - such as The Great Barrier Reef - urban - such as a city or town 5. Biome level: a group of communities that have similar structures and habitats extending over a large area. 6. the biosphere: the sum of all ecosystems in the biosphere

Question 59

habitat

Answer 59

'the environment in which an organism lives (address)' some organisms will have a specific habitat consisting of a narrow range of conditions e.g. snow daisy - found only on snowy range near mount buller some organisms will have a specific habitat consisting of a narrow range of conditions. e.g. Sydney rock oyster - while found along the east coast of Australia, it is only found in a band between low and high tide other organisms will have a habitat that consists of a greater variety of conditions e.g. flying fox - found in tall forest, paperbark swamps, mangroves, urban areas other organisms will have a habitat that consists of a greater variety of conditions e.g. migratory animals such as whales migrate through the year.

Question 60

micro-habitat

Answer 60

'small, particular part of a habitat in which particular organisms live' slightly different environment compared to the overall habitat, such as lower temperature or less sun e.g. beneath the bark of a tree within a forest habitat

Question 61

niche

Answer 61

'role of an organism/species in an ecosystem' competitive exclusion principle states no two species can have the same niche in an ecosystem a niche essentially is an organisms life 'job', i.e. a niche is what an organism does, and when, where it does it.

Question 62

competition between species

Answer 62

there are two types of interactions species can experience: - intraspecific competition occurs between two members of the same species, e.g. two males competing to mate with a female - interspecific competition occurs between two different species, e.g. two carnivores hunting the same food

Question 63

intraspecific competition

Answer 63

evolution acts at this level - which individual is most 'fit' to survive and mate? may be for food, shelter, mates, water, space or any resource in limited supply

Question 64

interspecific competition

Answer 64

indifferent species use the same resource, they can complete for that resource e.g. in dense forests, plants are continually competeing with each other for light/

Question 65

competition drives evolution

Answer 65

interactions can be: - beneficial - benign - harmful

Question 66

types of interactions between species

Answer 66

``` mutualism commensalism parasitism amensalism predation ```

Question 67

mutualism

Answer 67

beneficial interactions involves an intimate association between two species that offers an advantage to both two types: 1. obligate: both species completely depend on the other, e.g. some plants can only be fertilised by a single species. 'Darwins moth' - first proposed by Darwin when he saw the orchid Angraecum sesquipedale. the moth was only discovered 21 years after Darwin's death but did have the adaption Darwin described must be present 2. facultative: both benefit but dont rely on the other, e.g. ants 'farm' aphids and look after them for food (sugar solution) secreted by the aphids. however, neither need the other for survival as they could survive through other means

Question 68

commensalism

Answer 68

benign interactions involves two species forming an association where one organism, the commensal, benefits and the other is neither harmed nor helped e.g. birds

Question 69

parasitism

Answer 69

harmful interactions is a common exploitative relationship in plants and animals, where one organism (parasite) exploits the resources of its host organism (e.g. food, shelter, warmth) the host is harmed but not usually killed many parasites need more then one host in their life cycle e.g. plasmodium, the species causing malaria, needs to pass through mosquitoes as part of its life cycle harm to the host include: - reduced life span - impaired functions such as digestion or reproduction - less ability to withstand stress such as drought ot cold - greater vulnerability to predators parasites can be internal (endoparasites) or external (endoparasites) e.g. internal - roundworms, external - flea parasitoid - host is killed to the benefit of the parasitoid

Question 70

amensalism

Answer 70

harmful interactions refers to an association where one species is harmed or killed but the other is unaffected e.g. if an elephant steps on an ant

Question 71

predation

Answer 71

harmful interactions | killing living organisms (prey) for food.

Question 72

feeding

Answer 72

all organisms require energy to survive autotrophs can make their own food - plants, phytoplankton heterotrophs must consume other organisms - everything else, animals, insects, parasites, decomposers, etc

Question 73

species in an ecosystem are independent

Answer 73

within a given ecosystem, all species rely on the others if one species is removed, any species that interacts with it will be affected this can have far reaching effects

Question 74

food chain

Answer 74

links organisms according to feeding relationships | arrow shows the direction of flow of energy and matter through the chain

Question 75

producers

Answer 75

autotroph: organism that can make its own organic molecules, including glucose through the process of photosynthesis or chemosynthesis always at the start of a food chain

Question 76

consumers

Answer 76

heterotroph: organism that must obtain organic compounds by eating other organisms or their products include: - herbivores - carnivores - scavengers - parasites - detritivores - decomposers classified based on the type of organism fed on and type - first order consumers eat plants - second order consumers eat herbivores...etc - top consumers or top predators are the last link in food chains

Question 77

detritivores

Answer 77

detritus: consume organic wastes, including faeces and dead tissues they are different to decomposers as they do not break down materials outside their bodies important as they physically break down litter into small particles to make it easier for decomposers to then work e.g. worms, snails, dung beetles

Question 78

decomposers

Answer 78

break down complex molecules of the organic material in or on which they live decomposers like fungi and bacteria secrete enzymes that break down the material, and then absorb the broken down products as food

Question 79

food webs

Answer 79

food chains are rare in nature, most organisms consume more than one food source feeding patterns in an ecosystem is shown as a food web trying to understand food webs is vital as changed to one part will impact other parts the simpler the food chain (e.g. the giant panda only eats one type of food), the more sensitive it will be to changes

Question 80

keystone species

Answer 80

a species that plays a critical role is maintaining the structure of their ecosystem this could be by: - keeping population numbers of other species in check - influencing the habitat (eating tree/shrubs e.g. elephants: spread seeds through their dung, modify habitat by removing small trees and bushes, maintaining plain, make paths that act as fire breaks, can provide water for other species by digging water holes in river beds understanding what species in an ecosystem are keystone species is particularly important for conservation efforts.

Question 81

population dynamics

Answer 81

population size: total number of organisms in the population (in an area) total abundance: total number of organisms on a planet population density: number of organisms per unit of area

Question 82

population growth and size

Answer 82

population growth rate: the change in the total population per unit time natality (birth rate): the number of organisms born per unit of time mortality (death rate): the number of organisms dying per unit of time migration: - immigration: organisms moving into a population - emigration: organisms moving out of the population

Question 83

exponential growth

Answer 83

'rapid increase in the size of a population' exponential growth is sustained only when there is no environmental resistance species that experience exponential growth tend to have: - short generation time - have large numbers of offspring

Question 84

logistic growth

Answer 84

when population size is below the carrying capacity, the growth is rapid as the population size approaches carrying capacity, growth slows and stops

Question 85

factors affecting population size and density

Answer 85

all populations have the potential for exponential growth but many factors usually act to prevent this DENSITY INDEPENDENT FACTORS abiotic factors that influence tolerance range: - temperature - soil/water pH - rainfall - wind major changes to environment - natural disasters, e.g. fire, drought, volcanic activity - human caused changes, e.g. construction, pollutions TOLERANCE RANGE all species have requirements to survive for most conditions, species require a variable (e.g. temperature) to remain within that range, 'goldilocks zone'

Question 86

density dependent factors

Answer 86

``` food supply (increase density = compete for more resources) disease (increase density = spread disease and parasites more readily) competition (increase density = compete for more resources) predation (increase density = more easily found by predators) ```

Question 87

carrying capacity

Answer 87

maximum population that can be sustained before organisms run out of environmental resources total carrying capacity is dynamic - it will change as the conditions change