Introduction
1. A B
2. A B C D
3. A B C D
4. A B E
5. Among many possible answers:
Insects are inexpensive to maintain in laboratories
Insects reproduce rapidly, allowing many generations and large sample sizes in short periods of time.
Insects do not evoke the moral considerations that necessarily come to mind with use of mammals, particularly humans, in science.
Insects are easily manipulated because they cannot "object" to a treatment
6. Among many possible answers:
Humans have a "mind of their own" and may not follow orders concerning treatment.
Doing experiments with humans is often morally objectionable.
Mammals are very expensive to maintain in the laboratory, requiring large amounts of space and effort.
Mammals reproduce relatively slowly, so it is difficult to achieve large sample sizes in short periods of time.
1. B C
2.
3. A, C, D
1. B, lower in solute concentration than the cell
2. Being very small and therefore having a high surface area:volume ratio, diffusion and osmosis are very effective at moving solutes and water between an arthropod and its environment. Water loss, therefore, is a serious problem for terrestrial arthropods. A waxy coating, impermiable to water, would greatly slow down the loss of water.
3. You would expect them to be small, as diffusion of solutes from the body fluids into the organs would be efficient only over short distances.
4. There are a lot of possible answers to this question. email me or talk to me if you want to know if you are on the right track.
5. All decrease with increasing body size except running speed, which is not a function of body size and is therefore unaffected.
Evolutionary patterns
1. Our understanding of the evolutionary relationships among
the different bacteria is rudamentary. This results in a "poorly
resolved" or bushy tree.
2. The Hemichordata (acorn worms and pterogranchs) are the sister group (most closely related group) to the sea urchins, star fish, and other Echinodermata.
3. The Filicopsida (ferns) are the living group most closely related to the seed plants (Spermatopsida).
4. In my opinion, the close evolutionary relationship between fungi and animals is most surprising; until very recently, the fungi were assumed to be more closely related to the plants. Note that there is no single right answer to this question!
5. The trees shown (there are three of them) are all models of the possible evolutionary relationships among these three groups. Note that there are three groups, and thus three possible relationships - and all three have been postulated. For this reason, the evolutionary relationships presented at the top of the page are represented as a "bush". No one is sure at this time which two of the three groups are more closely related to each other.
6. Look at page 485 in the text for these answers. Good
examples (that are simpler to remember) would include:
Archaea vs. Bacteria: chemistry of the cell membrane
Archaea and Eukarya: transcription of RNA to proteins is
similar; chemistry of proteins associated with DNA is similar
Archaea vs. Eukarya: shape of chromasome (circular in Archaea,
linear in Eukarya).
7. These trees are two alternative models. The other
parts of the scientific method that are present include:
Goal - to understand relationships among bacteria, Archaea, Eularyotes
Models - these trees
Data - similarities and differences in DNA (small subunit RNA genes)
and similarities and differences in morphology
Evaluation - each of these data sets would cause us to support one
tree and reject the other
Revision - no revisions are presented in the text
Protista
1. Diffusion and osmosis are effective means of transporting molecules only over short distances. The complexity of eukaryotic cells such as protista includes organelles that specialize in moving nutrients and waste products into, within, and out of the cell eliminating the reliance on diffusion and osmosis. Therefore, these cells can be much larger in size.
2. Colonial protistans are made of cells that, if separated, can survive individually. The cells composing a multicellular organism cannot survive long if separated from other cells because some degree of specialization has occurred in cell function.
3. The structural and genetic similarity between mitochondria and certain oxygen-requiring bacteria, and similar similarity between chloroplasts and photosynthetic bacteria. Cell structures whose origins are not explained by this model include the nuclear membrane and the cytoskeleton.
Animals
1. Separate the cells and see if they can survive individually.
2. Protista does not include all decendents of a common ancestor (if it did, we would be protists). Animalia does include all decendents of a common ancestor.
3. The exoskeleton and endoskeleton are organized around joints. Muscles working across these joints can move the joint in very specific and controlled fashion.
4. Because a bilaterally-symmetrical animal can place many of it's sensory organs where they will not be fouled by it's own excrement, increasing their efficiency at gathering information.
5. A sessile radially-symmetrical animal can sense food coming from any direction if it has sensory organs around its periphery. Since it has to sit and wait, it needs to be aware of what is coming to it.
Energy and carbon
1. B
2. D
3. C
4. A
5. Tulip: autotrophic photosynthesizing
paramecium: heterotrophic respiring
dragonfly: heterotrophic respiring
mushroom: heterotrophic respiring
6. D
7. C
8. B
9. A
Homeostasis
1. The larger Monitor lizard will maintain a steady body temperature
with less effort than the Anolis because, being larger, it will gain
and loose heat more slowly.
2. C, E
3. The protista are much larger than the bacteria, and in order to maintain chemical homeostasis (gas exchange, intake of nutrients, expulsion of wastes) these larger cells require much more complicated structures. Diffusion (and osmosis) are insufficient because of the much lower surface area / volume ratio.
4. Ectothermy requires much less energy (less food) and ectotherms tend to spend much less time hunting and eating. Endotherms can be active in a much wider range of ambient temperatures because they do not rely on the environment to regulate their body temperature.
5. It is not likely to help most obese individuals, and might border on unethical dependent upon how the marketing was done. (btw, it is already happening - do a search on line for Leptin)
6. Total calary intake relative to activity levels is probably the best mechanism for controlling weight.
Nutrition
1. A, B, D
2. A, B, C, D (all true)
3. (all true)
4. Generalist herbivores that eat different parts of plants and
different species (like deer) will have an easier time meeting their nutritional
requirements compared to those that eat only leaves or only bark.
Vertebrates or insects that eat many different species of plant will have
an easier time meeting their nutritional requirements compared to insects
that eat only one part of a single species of plant.
5. Insects require much less energy and carbon (much fewer total
resources) to grow from larvae to adult and reproduce because they are
much smaller.
Foraging
1. E, 2. B, 3. D, 4. C, 5. A
6. This could actually be argued either way, and I'm not sure anyone has investigated this!
7. These are all social animals, and acting in packs they are effectively larger than their prey (total mass of predatory animals is greater than of the single prey).
8. low nutrient content (particularly proteins) <> eat a lot
of plant material
slick cuticle <> silk to stick to plant, or going inside (insects
that tunnel inside leaves or stems)
phytochemicals <> enzymatic compounds to "disarm" phytochemicals
low water content <> water conservation, drinking, avoiding sunlight
9. prey can hide <> predator can develop sensory systems to
improve searching ability
prey can sequester phytochemicals (herbivorous prey) <> predator
can eat everything except where the chemicals are stored; predator
can itself sequester the chemicals for defense
prey can mimic inedible animals or non-organic things (dead leaves,
bumps on logs) <> predator can improve searching ability
10. Predators that themselves must search for their prey are at greater risk of becoming prey of larger predators. Predators that ambush prey can evolve camouflage and thus reduce their chances of becoming prey. (one quandary for biologists is: are camouflaged ambush predators like praying mantids hiding from their prey or their predators?)
11. Plants and host animals have evolved many chemical and non-chemical defenses against herbivores and parasites, respectively. These defenses are usually specific for a certain type of attack. For instance, many phytochemicals inhibit insect growth or mimic insect hormones in order to disrupt development. In order to be successful, these consumers must therefore evolve counter-measures that are specific to their plant or host. Predators, killing and eating an animal, are not often having to deal with such specific counter-measures from their prey.
12. You would expect the soil and water to be poor in those nutrients that are provided by insects: proteins, or more particularly nitrogen.
Sensory systems
1. A: mechanoreceptor; B: chemoreceptor; C:
mechanoreceptor; D: mechanoreceptor; E: chemoreceptor;
F: visual sensor; G: visual sensor
2. Dragonflies are fast-moving predators that capture their prey on the wing.
3. A: false; B: true; C: false; D: true
4. "sound" is vibration of a substrate (air, water, or solid).
5. B, D
6. visual signals controlled for in B, D; "right" and "left" controlled for in B; acoustical signals are controlled for in C; chemical signals are controlled for in B, C and D (note that in A there is only one treatment, so nothing is being varied and thus nothing can be tested or controlled for).
7. genetic variation is present, phenotypic variation results (more than one scent), and variation iin survival results from phenotype. Evolution through natural selection can occur
8. There is no evidence of genetic variation, and the phenotype
"capture hens" reduces survival. Evolution through natural selection
cannot occur.
Experiments
1. genotype of milkweed leaves, age of milkweed leaves, amount of corn
pollen, genotype of butterfly larvae: neither controlled for nor
manipulated nor measured
genotype of corn pollen - partially manipulated, partially uncontrolled
number of larvae per dish; environmental conditions: controlled
for
weight gain / 3 days; survival of larvae: measured (response
variable
2. any uncontrolled, unmanipulated variable could be a cause if it differed systematically among the three groups
3. environment (tropical, temperate); day length (summer or winter)
, bat species: controlled for: chirping and warbling frogs
were observed on the same nights.
frog genotype: neither controlled for, manipulated, nor measured
number of matings for each male; survival of chirping and warbling
males: measured
Note: as this is an observational study, no variables are manipulated
4. environment (water quality, temperature, etc): controlled
for
; pillbug genotype: uncontrolled
; predator simulation: manipulated
; pillbug behavior. measured
5. B, D if songs are transmitted through vibrations of the floors
6.
Digestion
1. They may produce vitamins as metabolic by-products, or digest
materials the host cannot.
2. Cattle, iguanas, and termites have symbiotic gut bacteria that digest cellulose. Leaf-cutter ants have fungal symbionts that they "garden" that digest the cellulose in the leaves they harvest.
3. refer to the lecture notes.
4. Digestive enzymes are released at the gut surface and must diffuse out until they encounter the material they can digest. Nutrients ready to be absorbed must diffuse to the gut surface before they can be taken up.
5. To avoid digesting the cell itself.
1. Observational. No manipulations to test causal models
are being performed.
2. competition and predation
3. location: randomized,
presence or absence of starfish: manipulated
number of mussels: measured
number of species of sessile invertebrates: neither manipulated,
measured, nor controlled for.
4. measured
5. starfish appear to be keystone predators in the first experiment;
mussels appear to be facilitating species in the second experiment.
The first experiment does not address the question of facilitation because
the appropriate variables were not measured and cannot be said to test
that model. The second experiment does not reject the "keystone predator"
model, but also does not reject the "facilitation" model.
6. Because resources are lost each time an organism consumes
another organism, many prey are required to support each individual predator.
7. The food chain.
Why Sex
1. Haploid refers to one copy of each gene present in an animal (eggs and sperm are haploid). Diploid refers to two copies of each gene present in an animal (zygotes, embryos, and all tissues in an adult are diploid).
2A. When a female aphid "matches" the host plant she has found,
it is beneficial for her to reproduce offspring that are identical to herself,
which can only be done through asexual reproduction.
B. When the host plant is not a good match, or its condition
starts to deteriorate (perhaps through the feeding activities of the aphids?),
it is advantageous to reproduce sexually, where all offspring will be genetically
unique. This improves the chances that at least a few of them will
fiind host plants that they "match".
3. true: A
4. If the advantages to reproduction outweigh the costs to survival.
Sensory systems
1.