chapter 10: adaptations and diversity

Question 1

how genetic diversity allows populations to survive in a changing environment

Answer 1

• evolution by natural selection
  
  • those best suited to environmental changes survive and reproduce
  • results in species with adaptations that are suited to the environment
  • relies on populations having variation
    if populations don’t have genetic diversity, if conditions change, entire populations can be lost

Question 2

describe three factors that can affect gene pool of population

Answer 2

• mutation: lead to increased genetic variation - are the source of all new variation
  
  • Inherited mutations give rise to new alleles that provide variation within populations.
  • can include gene insertion, deletion, duplication
• natural selection
  
  • natural selection is the selection of favourable characteristics
  • the population has variations, where some are better suited to the environment and others are less suited
  • those better suited to survive and reproduce, passing on their characteristics
  • those less suited may die or not reproduce
  • next generation has more organisms with the better-suited features
• random events - eg. hurricanes, can wipe out individuals of a population with a specific gene

Question 3

how humans can use technology to allow our survival outside our normal tolerance range

Answer 3

• humans use of technology to extend the limits of our natural tolerance range
• enabling people to survive in hostile environments on and beyond Earth
• scuba tanks enable humans, who are air-breathing mammals to enter aquatic environments
• equipment and hi-tech clothing enable a mountaineer to survive a climb to the peak of a tall mountain
• sophisticated transport, living quarters and spacesuits enable astronauts to live on the International Space Station and to conduct spacewalks

Question 4

what are physiological adaptations

Answer 4

Internal features or processes of an organism that enable them to survive in a given environment

Question 5

examples of physiological adaptations

Answer 5

• vasoconstriction of blood vessels that conserves heat
• camels produce concentrated urine and little perspiration to reduce water loss
• snakes produce venom to paralyse prey → makes them easier to digest

Question 6

what are behavioural adaptations

Answer 6

activities that an organism performs in response to internal and external stimuli

Question 7

examples of behavioural adaptations

Answer 7

• huddling in penguins to stay warm
• migration of birds to warmer regions over winter
• bears hibernate in winter to preserve energy and survive cold temperatures

Question 8

what are structural adaptations

Answer 8

physical features of an organism that enable them to survive in a given environment (don’t confuse with physiological eg. poisonous spikes is physiological not structural)

Question 9

examples of structural adaptations

Answer 9

• blubber in seals → a protective layer from the cold temperatures of the ocean
• polar bears have small ears to reduce heat loss
• succulents have short, thick stems to store water

Question 10

adaptations desert animals have to survive low water availability

Answer 10

• burrowing frog: burrows themselves in mucous until it rains (behavioural-the burrowing bit, physiological- the making mucous bit)
  
  • It digs itself out and lays eggs in the puddles
    created by the rain
• tarrkawarra: produces very concentrated urine, does not need to drink (physiological)
  -It uses water made in cellular respiration and from food
• migratory birds: move to where resources, like water and food, are (behavioural)
• survival by reproduction:
  
  • species survive through offspring

Question 11

adaptations desert plants have for survival and reproduction to maximise water uptake

Answer 11

• tap roots (deep roots): to access deep water
• shallow, horizontal roots: to absorb rain water
• many small roots: to absorb greater amounts of water
  drought tolerant seeds:
  plants have seeds that only germinate when water gets in

Question 12

adaptations desert plants have for survival and reproduction to minimise water loss

Answer 12

• close stomata during the hottest part of the day
• have a thick waterproof layer
• small number of stomata
• sunken stomata: located below the leaf surface, create a region of relatively higher humidity in the air space around the stomata→reducs water loss thru transpiration (concentration gradient is similar)
• no/reduced leaves
• silver leaves: absorb less light → less evaporation
• hair on the surface: they slow the flow of air across the leaves, reducing the rate of water lost through transpiration.

Question 13

Explain how plants survive in freezing conditions

Answer 13

1. temperature drops below freezing
   
   2. cytosol has greater concentration of ions than the outside of the cell
   3. cytosol has a lower freezing point so ice doesn’t form within cell
   4. ice forms outof cell
   5. concentration of water inside cell is now higher than outside, so water moves out
   6. ice crystal continue forming outside of cell (don’t damage membranes, which are pliable)
   7. concentration of ions in cytosol continue to increase, further lowering freezing point (acts as antifreeze)
      
      1. this is because water with dissolved substances (ions) have lower freezing point than pure water

Question 14

define ecosystem

Answer 14

ecosystem: biotic and abiotic factors and their interactions

Question 15

define community

Answer 15

community: living components of an ecosystem (all of the populations of diff organisms living at the same time in the same location)

Question 16

define population

Answer 16

-population: a group of the same species living in the same area at the same time
- species: organisms that can breed and produce FERTILE OFFSPRINGS

Question 17

Explain how energy is gained and transferred within ecosystems

Answer 17

• producers use photosynthesis to capture sunlight energy and convert it into chemical energy in the form of glucose
  
  • this makes it available within the community
  • energy is transferred through consuming other organisms
    energy transfers are shown in food chains/webs

Question 18

producers

Answer 18

• photosynthetic organisms that, given a source of energy, can build organic matter from simple inorganic substances
• bring energy from an external source into the ecosystem.

Question 19

consumers

Answer 19

• organisms that obtain their energy and matter by eating matter of other organisms; also termed heterotrophs
• rely directly or indirectly on the chemical energy of producers

Question 20

decomposers

Answer 20

• organisms, such as fungi, that can break down and absorb organic matter of dead organisms
• different from other consumers because, as they feed, they chemically break down organic matter into simple inorganic forms

Question 21

what are keystone species

Answer 21

species whose presence in an ecosystem is essential for the maintenance of that ecosystem

Question 22

example of keystone species and consequence of its removal

Answer 22

• elephants are a keystone species of the grasslands of Africa
• elephants consume smallshrubs that would otherwise grow into trees
• they knock over large shrubs when eating
• elephants control the populations of trees on the grassland, maintaining the ecosystem as an open grassland
• herbivores of the grasslands feed by grazing and depend on the existence of these grasslands.
• thepredators of the grasslands depend on the open nature of the grasslands for hunting and catchingprey
• removal of the elephants would, over time, lead to the loss of grasslands and their conversion to woodlands or forests.

Question 23

what is mutualism + examples

Answer 23

• relationship between two different species in a community where both benefit
• example: mistletoe birds and mistletoe plants
  
  • birds depend on mistletoe fruits for food and, in turn, act as the dispersal agents for these plants
  • the birds eat the fruit but the seed is not digested
  • it passes out in their excreta onto tree branches where it germinates.
• example: coral and algae
  
  • coral protects algae and provides it with compounds required for photosynthesis
  • the algae produces oxygen for coral and helps it remove wastes

Question 24

what is commensalism + examples

Answer 24

• association between two different species in a community where one benefits and the second is not affected (no benefit or harm)
• example: clownfish and sea anemone
  
  • clownfish live among the tentacles of the sea anemone and are unaffected by their stinging cells
  • clownfish benefits by obtaining shelter and food scraps left by the anemone
  • anemone appears to gain no benefit from the presence of the fish.

Question 25

what is parasitism + examples

Answer 25

• interaction within a community that involves one species, the parasite, living on or in another species, the host
• example: fungi, such asTrichophyton rubrum
  
  • feeds on moist human skin, causing tinea and athlete’s foot.
• example: roundworms and tapeworms
  
  • endoparasites in the guts of mammals, such as the beef tapeworm and the pork tapeworm

Question 26

State the factors that affect population size

Answer 26

• primary ecological events
  - births
  - deaths
  - immigration (movement into population)
  - emigration (movement out of population)
  
  • secondary ecological events: influences one or more of the primary events
    
    • environmental factors can also affect the size of populations
    • eg. weather events
    • predation
    • disease

Question 27

density independent factors

Answer 27

• density-independent factors: factors whose impact on a population is not affected by the density of the population (abiotic factors)
• affects all individuals in a population regardless of its denisty
  
  • climate
  • sunlight available
  • natural disasters

Question 28

density dependent factors

Answer 28

• density-dependent factors: factors whose impact on members of a population is dependent on the density of the population
• change in their severity depending on the density of the population;
  
  • disease
  • competition
  • predation

Question 29

Why can populations not maintain a J-curve?

Answer 29

• j curve: the exponential or unlimited growth model (J curve)
  
  • conditions required to maintain j-curve include unlimited resources such as food and space
  • this can last for only a few generations.
  • every habitat has limited resources and can support populations of only a limited size.

Question 30

Define carrying capacity and draw a graph of its shape

Answer 30

• carrying capacity: the maximum (upper limit of) population size that a habitat can support in a sustained manner (upper limit of population size the environment can maintain)
  
  • s curve: logistics/density-dependent model

Question 31

tolerance range

Answer 31

extent of variation in an environmental factor (abiotic factor) in which a species can survive

Question 32

limiting factors

Answer 32

environmental condition that restricts the types of organism that can survive in a given habitat

Question 33

adaptations

Answer 33

structural, behavioural or physiological feature that enhances the survival of an organism in particular environmental conditions.

Question 34

competition

Answer 34

interaction between individuals of the same or different species that use the same resources in the same ecosystem

Question 35

adaptations aquatic animals have to survive in cold conditions

Answer 35

• antifreeze substances (physiological)
  
  • some animals make antifreeze substances like glycerol during the start of freezing season
  • These antifreeze substances are released into their body fluids, which lowers the fluids’ freezing point to well below that of the surrounding water temperatures
  • This means that the body fluids of these organisms stay liquid.
• burrowing (behavioural)
• hibernation (behavioural)
• huddling (behavioural)
• growth of thick fur and layers of fat (structural)

Question 36

conditions needed for the survival of coral reef

Answer 36

coral reef:

• temperature between 18 degrees celsius and 40 degrees celsius (optimal temp is between 23 and 29)
• very saline (salty) water
• water must be clear so light can penetrate through it (photosynthetic alage lives in coral tissues)

Question 37

genetic diversity

Answer 37

the variety of genes or the number of different inherited characteristics present in a species

Question 38

conditions required for the survival of a terrestrial organism

Answer 38

conditions can include: sunlight, oxygen, water availability, temperature

Question 39

distribution of population

Answer 39

• refers to thespread of members of a population over space.
• can be:
  
  • uniform: trees and plants in farms
  • random: bacteria
  • clumped: packs of wolves, corals

Question 40

where does variation come from

Answer 40

Variation comes from
Mutations
Sexual reproduction
Gene flow

Question 41

what are K selected species

Answer 41

K selected species put a lot of effort into each individual offspring
Humans, albatross, sharks

Question 42

what are r selected species

Answer 42

r selected species put little effort into individual offspring
Insects, cane toads, coral

Question 43

features of K selected species

Answer 43

Long lived
Few offspring
Reach sexual maturity late
Much energy is used for each young
Low mortality
Slow population growth
Suited to stable environments

Question 44

features of r selected species

Answer 44

Short lived
Many offspring
Reach sexual maturity early
Little energy put into each offspring
High mortality
Quick population growth
Suited to unstable environments – they can increase in size quickly when conditions become favourable

Question 45

cool burning

Answer 45

• occurs early in dry season
• reduces fuel load of area (ferocity of potential bush fires is reduced, decreasing damage to environment)
• stimulates growth, eucalyptus needs fire for seeds to germinate
• helps maintain biodiversity - fewer hot burns occur, so species don’t lose all their food and habitat resources

Question 46

observations by Indigenous people allow for them to survive

Answer 46

• mimicked kangaroos
• Aboriginal Australians designed a similar ‘pouch’ to carry their babies
• hands were free to carry other things, and the energy expenditure to carry their child was reduced.
• Weapons and tools made by Aboriginal and Torres Strait Islander peoples used the stingray barb as a spear tip.

Question 47

factors affecting biodiversity

Answer 47

• larger areas tend to have a larger number of species
• 10x larger -> twice as many species
• the distance from equator also affects number of species
• the closer the ecosystems are to the equator, the more species that exist
• equatorial areas are warmer and have more moisture -> more photosynthesis can occur

Question 48

factors that decrease genetic diversity

Answer 48

• selective breeding
• gene drift
• natural selection