Chapter 3 - Physical Conditions

Question 1

What are conditions?

Answer 1

They are physiochemical features of an environment. (ex. temperature, humidity, pH, salinity in aquatic environments). Organisms often alter the conditions of their immediate environment. Conditions can’t be used up.

Question 2

What are resources?

Answer 2

They are consumed by organisms in the course of their growth and reproduction

• ex. plants use sunlight, CO2, H2O and nutrients to produce biomass through photosynthesis
• ex 2. rabbit would be a resource for an eagle

Question 3

What is a response curve?

Answer 3

It is a representation of the conditions that induce a range of physiological responses in organisms, determining habitability - check pictures of graphs

Question 4

What are the 3 types of response curves?

Answer 4

1. Response to temp: extreme conditions are lethal, but in between is favourable (normal model)
2. Response to poison: if it is absent or present in low concentrations, it may not affect organisms, but once a threshold is surpassed, reproduction, growth and survival are affected
3. Response to amount of dissolved salts: it become toxic at high concentrations (but is required in low) and can be lethal

Question 5

What is a thermophile?

Answer 5

It is a specialized heat-loving fungi, bacteria or archaea that can survive in temperatures maintained at 60°C for long periods of time. They thrive & grow in high temps.

Question 6

What is a chilling injury?

Answer 6

It is when organisms are forced into extended periods of inactivity and cell membranes may break down due to body temperatures of a few degrees above 0 (ex. affects tropical fruits).

Question 7

What is a photoperiod?

Answer 7

It is the length of the period of daylight within a daily cycle that acts as an external signal for species.
- ex. winter is coming, so the photoperiod shortens, so organisms like bears develop thick coats

Question 8

What is diapause?

Answer 8

It is when the photoperiod shortens, so insects enter dormant phase that suspends development and their metabolic activity highly reduces within normal activities, which is known as diapause

Question 9

What is acclimatization?

Answer 9

It is when exposure to low temps leads to an increased rate of metabolism at that temp and/or increases the species tolerance to even lower temps. Individuals can acclimatize, but only populations can adapt over time.

Question 10

What is an ectotherm?

Answer 10

They rely on external sources of heat to determine the pace of their metabolism
- ex. invertebrates, amphibians, reptiles and most fish (as well as plants, algae, bacteria and archaea)

Question 11

What is an endotherm?

Answer 11

They regulate their body temp by producing heat within their body
- ex. mainly birds and mammals

Question 12

What is an acidophile?

Answer 12

They are microbial specialists that thrive in highly acidic environments

Question 13

What is photoinhibition?

Answer 13

It is when the rate of carbon fixation in plants decreases as the intensity of radiation increases - photoinhibiting photosynthesis

Question 14

What are sun leaves?

Answer 14

They are leaves that have full exposure to sunlight which causes them to be thicker, smaller, and colour-faded with more densely packed chloroplasts (that process incoming radiation) within cells and has more cell layers.
- leaf shape is an evolved characteristic (plasticity) that changes according to what the leaf experiences

Question 15

What are shade leaves?

Answer 15

They are lower in the canopy which makes them flimsy, thinner, bigger and broader, and intercept diffused/filtered radiation and may supplement the main photosynthetic activity of sun leaves high in the canopy
- leaf shape is an evolved characteristic (plasticity) that changes according to what the leaf experiences

Question 16

What are avoiders?

Answer 16

They have short lifespans and their photosynthetic activity is concentrated in periods when H2O is readily available. The remainder of the year, they remain dormant as seeds.
- ex. desert annuals, annual weeds and crop plants

Question 17

What are tolerators?

Answer 17

They produce long-lived leaves that transpire slowly and they tolerate drought/low water conditions meaning, but their highest photosynthetic rate is actually quite slow

Question 18

What is a deciduous tree species?

Answer 18

They lose their leaves for at least 1-4 months or more per year

Question 19

What is a C3 pathway?

Answer 19

They are used by the majority of plants, algae and photosynthetic bacteria. It produces sugars with 3 carbons from photosynthesis and plants that use this are highly productive photosynthesizers. However, they are wasteful with water, have a max rate of photosynthesis at low intensities and are less successful in arid areas

Question 20

What is a C4 pathway?

Answer 20

It is an alternate approach to C3 and it produces sugars with 4 carbons as an initial product. These plants are far more CO2 and H2O efficient (less H2O escapes because their stomata doesn’t have to be as open to get CO2). These plants are more uncommon and are inefficient at low radiations (poor shade plants).

Question 21

What is a CAM plant?

Answer 21

A crassulacean acid metabolism (CAM) plant is even more efficient than C4 because it opens its stomata at night to absorb CO2 and fix it as malic acid. It closes its stomata during the day and releases CO2 internally for photosynthesis, meaning less water is lost. This is usually found in cactuses.

Question 22

What are autotrophs?

Answer 22

They are green plants, algae, cyanobacteria and other photosynthetic bacteria that use photosynthetic radiation, water, nutrients and CO2 as their major resources.

Question 23

What are autorophs also known as?

Answer 23

They are aka primary producers that assemble CO2, H2O and nutrients into complex molecules (carbs, fats, proteins and nucleotides) and package the molecules into cells, tissues and organs

Question 24

What are heterotrophs?

Answer 24

They use packages made by autotrophs as food resources where they unpack, metabolize and then excrete some contents (like inorganics - CO2, H2O) and reassemble the remaining pieces into packages in the body. If this heterotroph is consumed, then the process occurs again.

Question 25

What does chemo-autotrophic mean?

Answer 25

It is usually a kind of bacteria that gets their energy by oxidizing reduced energy found in inorganic compounds (ex. hydrogen sulphides) and uses the energy to fix CO2 into organic matter (the same enzymes in C3)

Question 26

What are the 4 types of heterotrophs?

Answer 26

1. decomposers
2. parasites
3. predators
4. grazers

Question 27

What is a decomposer?

Answer 27

It is a heterotroph that feeds on already dead plants and animals

Question 28

What is a parasite?

Answer 28

It is a heterotroph that feeds on one or few host plants/animals while they are alive, but usually don’t kill them (at least immediately)

Question 29

What is a predator?

Answer 29

It is a heterotroph that eats many prey organisms, typically by killing them

Question 30

What is a grazer?

Answer 30

It is a heterotroph that consumes parts of many prey organisms, but usually doesn’t kill their prey (ex. rabbits eating plants)

Question 31

What is a generalist?

Answer 31

It is a species that feeds on a wide variety of foods, but they have a clear preference/rank order of what they will choose if alternatives are available.

Question 32

What is a specialist?

Answer 32

It is a species that may focus on particular parts of prey, but ranges over species. It is most common among herbivores because different plants are different in composition.
- ex. birds specialize on eating seeds, but are not restricted to certain species of seeds

Question 33

What is mutualism?

Answer 33

It is a relationship between two species that benefits both parties.
- ex. herbivores lack cellulolytic enzymes, so they enter a mutualistic relationship with cellulolytic bacteria and protozoa in their guts that have the appropriate enzymes

Question 34

What are defences?

Answer 34

They are are physical, chemical, morphological and behavioural defences that organisms develop to protect them from being attacked. They reduce the chance of an encounter with a consumer and/or increase the chance of survival in such encounters

Question 35

What are secondary chemicals?

Answer 35

They are used in the plant kingdom as a defence mechanism to deter herbivory

Question 36

What is a constitutive chemical?

Answer 36

AKA quantitative chemical, they make tissues that contain chemicals that make them indigestible and are produced even in the absence of herbivory attack

Question 37

What is an inducible chemical?

Answer 37

AKA qualitative chemical, they are toxic/poisonous even in small amounts and can be produced rapidly, so they are produced in response to damage

Question 38

What is crypsis?

Answer 38

It is when an animal matches its background, possesses a pattern disrupting its outline, or resembles an inedible feature of its environment to make it less obvious to predators. (ex. green colouring of grasshoppers)

Question 39

What is aposematism?

Answer 39

It is when a noxious/dangerous animal advertises the fact with bright colours and patterns so other animals do not eat it.

Question 40

What is mimicry?

Answer 40

It is when species mimic the patterns of distasteful (poisonous prey) so it will be avoided too even though it isn’t toxic

Question 41

What is intraspecific competition? What are the 2 types?

Answer 41

It is competition between individuals of the same species for limited resources.

1. Exploitation
2. Interference

Question 42

What is exploitation competition?

Answer 42

It is a type of intraspecific competition that occurs when competitors indirectly interact through shared resources. They deplete the resources available to each other.

Question 43

What is interference competition?

Answer 43

It s a type of intraspecific competition that occurs when competitors directly interact over resources.
- ex. vultures fighting over carcass

Question 44

What are vital rates?

Answer 44

They are the survival, growth and reproduction rates of a species that are affected by competition. They can be compared with what the rates would have been if there were more resources available

Question 45

What does density-dependent mean?

Answer 45

It means the more crowded an individual is by its neighbours, the greater the effects of intraspecific competition are.

Question 46

What is an ecological niche?

Answer 46

It is a summary of an organism’s tolerances and requirements (how the organism lives not where)

Question 47

What is a habitat?

Answer 47

It is where an organism lives and it provides many different niches

Question 48

What is an n-dimensional hypervolume?

Answer 48

It refers to niches being multidimensional, where n is the number of dimensions that make up the niche.

Question 49

What is toleration and avoidance?

Answer 49

They are evolutionary strategies in which species will tend to do one over the other.
Ex. desert horned lizards can tolerate the heat, but tend to avoid it by going underground

Question 50

What is Bergmann’s rule?

Answer 50

It says that mammals tend to be bigger in cool habitats because the surface area to volume (SA/V) ratio is lower, so the animal is less exposed to the elements. For animals in warm habitats, they tend to be smaller because a higher SA/V ratio allows it to diffuse heat across the body’s surfaces so it doesn’t overheat. Rule works well for homeotherms.

Question 51

What is C:N ratio?

Answer 51

In plants, there are lots of carbs (C) and less protein (N), so when they are eaten, the animal is protein-rich, so its excrements are carbon-rich