Solutions to various types of tasks are below.


Biol unit 2 exam 2007
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Q1a mosquito community

I will keeping adding the solutions gradually. Be patient please.

Any exam related questions can be posted here. revision page

Muliple choice section
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Short answer
Question 1
a. see diagram
b. photosynthesis
c. possible answers see diagram
d. great blue heron or racoon AND marsh hawk (thx to Lama for picking this up!)
e. mosquitoes provide a link between the producers and the rest of the consumers, allowing the flow of chemical energy to the rest of the organisms. each stage in their life cycle also contributes as food to other orgnaisms in the community.

Question 2 (you should be familiar with this question already)
a. avoid predation by poisoning predators and communication between females about to lay eggs to avoid c
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Q1c food chains
ompeition for same space
b. competition for space to lay eggs and therefore allow tadpoles to grow with more resources
c. biological
d. another organism (cane toad) was used to control the population different species (sugar cane beetle)

Question 3
a. looking at graph, 6.25mm (must include units!)
b. compare means you must include info about each species and you should also include a difference and a similarity if possible. For example, in general A. stuarttii did not rely heavily on one prey size, the proportion ranged form 0.25 to .1. In contrast, A. flavipes more than half of the diet was for one prey size (6.25mm). They were similar in that they both ate a range of insect sizes and for both there was only one size they didn't eat.
c. They both ate a prey size that the other didn't, A. flavipes ate 16.25mm whereas A stuartii ate 18.75mm. Their main prey size was also different to each other (A. flavipes had 6.25mm and A. stuartii 3.25mm) By also having a range of different prey sizes to resort to, this would reduce competition.
d. possible answers include, both nocturnal, habitat is same region (open forest North of Canberra)
e. reproductive strategies might be different, eg offspring are born at different times of the year, partly arboreal could allow them to occupy different microhabitats within the forest

Question 4
a. going down each pathway, LHS = parathyroid gland, parathyroid hormone, bone cells (osteoclasts), breakdown of bone and releasing clacium into blodd; RHS = bone, increase amount of calcium deposit in bone
b. receptors
c.bone

Question 5
a. a leeway of any specific time between 4pm and 5pm (must include pm in your answer)
b. No, the highest temperature actually occurs earlier in the day at about 1.30pm
c. nervous system as it would involve receptors in skin that stimulate sensory neurons to convey information, or that body temperature responds to air temperature in relatively short time frame and therefore would involve the nervous system
d.Homeostasis is the maintenance of a steady internal environment despite changes in the external and environemntal condition

Question 6
a. neurotransmitter
b. hormone
c.diffusion through intersitual fluid (of synaptic gap)
d. nervous system
e. transmission of an electrical impulse along nerves is quicker compared to hormones travelling in blood
f. any endocrine organ will do here, eg. pancreas, testes, ovary, adrenal glands, thyroid gland, pituitary etc
g. horomone given here MUST match your answer to part f, eg insulin (pancreas)
h. answer here must match the hormone mentioned in part g and focuses on what happens in the taget cell, eg. results in an increased uptake of glucose from the blod into the target cell (liver)
i. motor or efferent neuron

Question 7
for each theme, a mark for describing a theme and a mark linking it to biological concept, possible answer: humans influence ecosystems, one way is the release of chemicals into environment that can then be passed along food chains and cause death of animals, death of animals can affect the balance of a food web, leaving more or less of a particular species that then further impacts on the ecosystem

Question 8
a. attract males to let them know that she is ready for reproduction
b. choose the right conditions before allowing fertilisation
c. eggs are cared for in a den protecting them from potential predators
d. female only reproduces once before dying, no parental care of larvae
e. no, it is internal fertilisation as females stores the sperm and presumably allows fertilisation of eggs within her body
f. artificial insemination, inserting sperm (obtained from males) into females
g. "AI' is not always successful because delivering the sperm is one thing, timing it with ovulation is another, also some females of a species require the physical act of courtship and mating to stimulate ovulation

Question 9
a. introduced species
b. diverse diet, breed rapidly, ideal environment
c. biological control is when one organism (the parasitic Orchitophyra) is used to control the population of another (the northern pacific sea star)
d. use of chemicals could lead to poisoning of organsims other than the sea star as the chemicals are not species-specific
e.
f. no matter what method was chosen, the pattern should be clear it is not an even distirubtion and that the density of sea stars is greater near rocks compared to the sandy ocean floor
g. rocks provide protection, rocks are where the prey of the sea star reside, rocks are where courtship/reproduction occurs
h. because sea stars eat mussels, this was a way of getting the parasite into the sea stars, without any physical human contact and also hopefully to a larger number of them
i. prevent any external factors from interfering with the abundance of sea stars and therefore adding another variable to the experiment
j. they did not control the fact that they gave dead mussels to area B and not to area A, they really should have provided area A with dead mussels that were not infected with the parasite