chapter 9-10

Question 1

Natural selection

Answer 1

Nature selects who would live and who wouldn’t ( different frog colour example

Question 2

asexual reproduction advantages and Disadvantages.

Answer 2

asexual reproduction:
–>ADVANTAGES
-only one parent is needed, does not rely on another organism less energy required to find a mate
-very quick process
-allows a single organism to quickly colonise a new area
–>DISADVANTAGES
-lack of genetic variation reduces the chance of a population adapting to a new environmental condition
-pressure on availability of recourses
- if conditions change entire population can be lost

Question 3

external fertilization features and where they occur

Answer 3

External fertilisation occurs when animals release their gametes into the external environment so that fertilisation occurs outside the body of females. Features of external fertilisation include the following:

Very large numbers of gametes are produced.

Large numbers of gametes increase the chance of fertilisation but also mean there is much gamete wastage.

aquatic environment

Question 4

Internal fertilisation

Answer 4

Internal fertilisation occurs when males deliver sperm directly into the reproductive tract of females so that fertilisation of eggs occurs inside the body of females. Features of internal fertilisation include the following:

It has an energy cost of finding, attracting and securing a female mate.

It has the benefit of increasing the chances of the gametes meeting, and therefore increases the chances of fertilisation.

It occurs in some aquatic organisms as well as in terrestrial organisms.

All terrestrial animals use internal fertilisation, except for amphibians, such as frogs and toads that mate in the water.

Question 5

Somatic cell nuclear transfer (SCNT)

Answer 5

The nucleus of a cell is removed, creating an enucleated cell.

The nucleus of another cell can be transferred to an enucleated cell to form a redesigned nucleated cell.

An enucleated cell can be fused with a somatic cell using a short electrical pulse

Question 6

Biodiversity, its importance and the three levels: Genetic, Species &
ecosystem.

Answer 6

Biodiversity can be defined as the “variety of life in our natural world” and is measured as the number of different species—including plants, animals, fungi, algae, and even microorganisms, like bacteria—that share a certain home region. Biodiversity is a key indicator of the health of an ecosystem.

Genetic diversity refers to the variety of genes or the number of different inherited characteristics present in a species. Different populations of the same species may have different levels of genetic diversity. Populations with a high level of genetic diversity are more likely to have some individuals that can survive and reproduce when environmental conditions change. Genetic diversity is created through mutations, or changes, in an organism’s DNA that are passed on to the next generation.

Species diversity refers to the variety of different kinds of organism living in a particular habitat or region; for example, the diversity of plant species of the Gibson Desert.

Ecosystem diversity refers to the variety of physical environments in which organisms live and with which they interact. They range from biologically rich ecosystems, such as coral reefs and rainforests, to biologically sparse ecosystems

Question 7

Genetic diversity importance

Answer 7

Genetic diversity:
increases species survival following environmental change

increases the number of individuals that can survive and reproduce

increases biodiversity in ecosystems

means natural selection can act, as there are many alleles to select from.

Question 8

abiotic factors

Answer 8

abiotic factors nonliving factor, such as weather, that can affect population size

Question 9

tolerance range

Answer 9

tolerance range extent of variation in an environmental factor within which a particular species can survive

Question 10

Adaptations for survival (Behavioural, Physiological, structural)

Answer 10

Structural
Physical features of an organism that enable them to survive in a given environment

Blubber in seals providing a protective layer from the cold temperatures of the ocean

Physiological
Internal and/or cellular features of an organism that enable them to survive in a given environment

Vasoconstriction of blood vessels that conserves heat and increases blood pressure

Behavioural
Activities that an organism performs in response to internal and external stimuli

Huddling in penguins to stay warm, migration of birds to warmer regions over winter

Question 11

limiting factor

Answer 11

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

Question 12

Survival without drinking: the tarrkawarra

Answer 12

he tarrkawarra, or spinifex hopping mouse (Notomys alexis), is a placental mammal that lives in sandy deserts in Australia (figure 10.9). Because it can survive without drinking liquid water, the tarrkawarra can endure long periods of drought. Its kidney tubules reabsorb almost all the water from the kidney filtrate so that it produces highly concentrated and almost solid urine.

Question 13

Survival by dormancy: frogs in the outback

Answer 13

The frogs then go into an inactive state known as dormancy, in which both breathing and heart rate are minimal and energy needs are greatly reduced. Their low energy requirements are met from their fat reserves.

They remain buried and are protected from desiccation until the next rains come; this may be a wait of one or two years.

They come out of their dormant state only when soaking rains fall and soil moisture rises. Once activated, the frogs return to the surface to feed and breed in temporary pools.

Question 14

camel survival

Answer 14

a double row of long eyelashes and slit-shaped nostrils that can be closed — both features protecting the camel from windborne sand particles (figure 10.15)

bony structures in their nasal passages that enable the water vapour in their outgoing breath to be absorbed; it is then exhaled as dry air

oval-shaped red blood cells; this enables the cells to continue circulating even when the viscosity (thickness) of the blood increases due to the camel becoming dehydrated and losing body water

the ability to produce very dry faeces because of a long colon in their gut

the inbuilt fat store in the hump; this is also a physiological adaption. As the fat stores are metabolised for energy production when food is scarce, the reactions also produce metabolic water for the camel.

Question 15

A biotic factor….

Answer 15

(living) — the populations of various species that live in a given region ex.aquatic plants, fish, amphibians, and algae

Question 16

Intraspecific
Interspecific

Answer 16

Intraspecific Competition for resources between members of the same species
Wheat crops competing for soil and nutrients
Interspecific
Competition for resources between members of different species Leopards and lions competing for the same prey

Question 17

Amensalism

Answer 17

Amensalism
One organism is inhibited or destroyed, the other is unaffected Elephants stepping on ants — the elephant is unaffected, however the ant dies

Question 18

Predator–prey

Answer 18

One species kills and eats the other Polar bears (predator) eat seals (prey) in the Arctic

Question 19

Herbivore-plant

Answer 19

An animal eats a plant
Koalas eating eucalypt leaves

Question 20

Parasitism

Answer 20

An organism living on or within another organism to derive a benefit, whilst harming the host A flea living on a golden retriever — the flea obtains food, however the golden retriever loses nutrients

Question 21

Mutualism

Answer 21

A beneficial relationship between two species
Hummingbird and bee balm flower — the hummingbird gets nectar, the balm flower spreads its pollen

Question 22

Commensalism

Answer 22

One member gains a benefit from the relationship, the other is unaffected
The clown fish and the sea anemone — the clown fish obtains shelter and food scraps, and the sea anemone is unaffected

Question 23

embryo splitting

Answer 23

1. Fertilization
   The process begins with in vitro fertilization (IVF), where an egg is fertilized by sperm outside the body. This fertilized egg is allowed to develop into an early-stage embryo, usually reaching the 2 to 8-cell stage.
2. Embryo Splitting
   At the appropriate stage (usually 2 to 8 cells), the embryo is carefully divided. Each of the resulting cells, or blastomeres, is capable of developing into a complete embryo because all the cells in the early embryo are totipotent (can develop into any type of cell).
3. Culturing the Split Embryos
   The individual cells from the split embryo are cultured separately in conditions that support their development. They are allowed to continue dividing and form new embryos, essentially creating identical twins or clones of the original embryo.
4. Embryo Transfer
   Once the embryos have reached a certain stage of development (usually the blastocyst stage), they are transferred into the uterus of a surrogate mother for gestation.
5. Pregnancy and Development
   If successful, the embryos implant in the uterine lining, leading to pregnancy. The surrogate mother will carry the cloned embryos to term.

Question 24

PTC its advantages and disadvantages

Answer 24

Tissue culture cloning of plants has several advantages:

Slow-growing plants can be produced in large numbers.

Plants can be cultured all year round in controlled conditions of temperature and day length, rather than relying on seasonal growth.

Virus-free tissue can be used to produce a large number of plants that do not carry the virus. (Viruses are responsible for many plant diseases that can affect commercial crops.)

Cultured plants can be transported from country to country. The sterile conditions in which they are cultured ensures that the plants are pest-free, so that lengthy quarantine periods are avoided.

Question 25

PTC : the process,

Answer 25

It begins with a small piece of a healthy plant, such as a piece of leaf, bud or stem. The plant that supplies the tissue is selected because it has particular desirable characteristics, such as flower colour, disease resistance or timber quality.

Pieces of a plant to be cultured must contain meristematic tissue because this is the only plant tissue that is capable of cell division by mitosis.

Question 26

R and K selected

Answer 26

r-selected populations have a ‘quick and many’ reproduction strategy.
K-selected populations have a ‘slower and fewer’ reproduction strategy. Features of K-selected populations include the following:

Question 27

carrying capacity

Answer 27

carrying capacity the maximum population size that a habitat can support in a sustained manner

Question 28

density-independent factors.

Answer 28

density-independent factors. This means that they affect all individuals in a population, regardless of the size of the population. So, a sudden frost will kill a high percentage of members of a population of frost-sensitive insects. It does not matter if the population size is small or large.

Question 29

density-dependent factors.

Answer 29

density-dependent factors. These are events that change in their severity as the size of a population changes. The impact of density-dependent factors varies according to the size of a population.

Examples of density-dependent factors include:

the outbreak of a contagious disease. The spread of this disease will be faster in a large, dense population than in a small,predation. Predators are more likely to hunt the most abundant prey species, rather than seek out prey from a small population.

competition for resources. Members of a population need access to particular resources. For plants, these resources include space, sunlight, water and mineral nutrients; for animals, necessary resources include food, water and space for shelter and breeding. These resources are limited in supply.