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What is a Keystone species? From 1963-1973 Robert Paine conducted a field experiment which aimed to determine the effect of predation on community composition of a rocky tidal shore community in Washington State. ? Describe Paine's experiment, his observations, and his conclusion. What was the keystone species in his study?

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Nelly StrackeLv2

7 May 2019

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To investigate Neilâs symptoms further, doctors referred him to a neurologist, Dr. Bonasera, that specialized in motor disorders. Dr. Bonasera noted that Neil exhibited diminished right dorsalis pedis and posterior tibial pulses. His cognitive tests were normal. Tests of the cranial nerves were normal, with the exception of occasional slurred speech. His motor tests revealed generally slowed movements. Neil was experiencing pain and stiffness in the shoulder joints, which could explain his restricted range motion. Dr. Bonasera tested the motor strength of his finger extensors (4+/5), hip flexors (4/5), and various muscle groups in his arms and legs (5/5). There were tests for dysmetria (i.e., lack of coordination) and dexterity, which were normal yet slowed. Neil did have difficulty lifting his legs for some of the examinations, and he walked with a shuffling gate, often keeping both feet close together for a narrow base of support. He took very small steps and often stooped over while walking. When placing one foot in front of the other in a tandem walking stance, he would fall to either side and was unable to regain his balance. Sensory examination was normal, deep tendon reflexes were normal, and the Babinski sign was absent bilaterally. There were no Parkinsons-like symptoms, increased motor tone, or muscle fasciculations observed in testing.

Just one day later, another neurologist noted brisk reflexes and bilateral Babinski signs. Doctors performed magnetic resonance imaging (MRI) of the brain to reveal an infarct in the right caudate nucleus and an infarct in the right cerebellum. Doctors prescribed intense physical therapy. Neil saw some improvements for articulation, but he continued to struggle with the speed of speech and began to experience weakness of the tongue on his left side. CT angiograms revealed an aneurysm of the infrarenal aorta extending into the right common iliac artery. A spinal MRI revealed degenerative disease of the cervical spine (C4-C5) with a mild central canal stenosis. No such degeneration was present in the thoracic or lumbar spine. However, Neil did have mild impingement of the right L3-L5 nerve roots. A lumbar puncture revealed normal CSF pressures, cell counts, and composition. Neil continued physical therapy and experienced significant improvements in speech, walking, and balance. He also commented that his muscle soreness and fatigue had improved.

Neil continued his physical therapy while recovering at home. However, his symptoms worsened over the following weeks. Neil grew progressively weaker, occasionally falling. He required assistance for walking, and he was experiencing some numbness in both hands. He was admitted to a hospital, where he underwent a neurological examination. Cognitive and cranial nerve tests were normal. There were no fasciculations of the neck or tongue muscles. He was able to rotate and extend the neck with normal strength, however neck flexion seemed to be compromised. Neil exhibited widespread fasciculations in his arms and legs, and the muscles of these limbs had mildly atrophied. Motor tests were conducted for the arms and legs (4/5), and wrist extensors and intrinsic muscles of the hand (3+/ 5). Neil exhibited hyperactive deep-tendon reflexes and positive Babinski signs bilaterally. Sensory examinations were unchanged.

Based on the compounding symptoms and rapid progression of the disease, doctors suspected that Neil was suffering from amyotrophic lateral sclerosis (ALS), a disease that results in the destruction of upper and lower motor neurons. To confirm this diagnosis, neurologists conducted a series of tests., including nerve conduction tests and needle EMG. Nerve conduction tests of the motor and sensory nerves revealed normal conduction velocities with low amplitude compound motor action potentials, and normal sensory nerve potentials. There were abundant fasciculations and characteristics that suggested remodeling of motor units following denervation. Furthermore, EMG suggested net motor unit loss. There was no evidence of demyelination. Based on these results, doctors confirmed the diagnosis of ALS. For the following weeks, Neil experienced physical therapy aimed to help him preserve his strength and energy. He soon began to experience difficulty swallowing, and his cough progressed. Soon thereafter he developed pneumonia, was placed on a feeding tube, and ultimately died just 15 weeks after his initial hospitalization.

5. Electromyography involves recording electrical activity from muscle fibers. Justify Neil's low amplitude compound motor action potentials given his diagnosis of ALS. Be sure to describe how a muscle fiber initiates and propagates action potentials, and state how that process differs in the case of ALS.

6. Motor unit remodeling includes a reduction in the number of motor units, atrophy of muscle fibers, and an increased number of fibers per motor unit. Describe how motor unit remodeling may be indicative of ALS. Be sure to describe the typical structure and function of a motor unit, a typical distribution of motor unit (and fiber types) within a muscle, and how motor unit remodeling could contribute to Neil's weakness.

7. Based on the etiology of the disease, justify the finding of hyperactive deep-tendon reflexes and positive Babinski signs bilaterally in a patient suffering from ALS. Be sure to describe a typical reflex, and describe how descending inhibition may modulate a reflex response.

8. Justify why Neil's motor tests progressively worsened, whereas sensory, and cognitive tests remained unchanged. Be sure to describe the central and peripheral nervous system structures required for perception versus movement, and identify where deficits may be found in a patient with ALS.

As temperatures in an African savanna increase and rainfall decreases, it would most likely change into

tiaga

desert

tropical rainforest

temperate forest

What is imprinting? Give an example.

fixed assocation, such as hatching ducks recognizing the first animal they see as their mother

a learned behavior, such as a wasp circling during a search for food, so that it can return to its nest

alteration of instinct, such as a spider changing the type of web it weaves depending upon the environment

Opportunistic species

provide extensive care for their offspring

produce many offspring

reproduce later in life

What are the five agents of microevolution?

gamete production; mating; fertilization; caring for offspring; formation of herds

photosynthesis; respiration; mitosis; meiosis; fertilization

mutation; gene flow; nonrandom mating; genetic drift; natural selection

Microevolution is

new species

minor extinction of species

changes in allele frequency in a population

Which of the following is does not help defend against predators?

Toxins made by plants that injure caterpillars feeding on the plant

The large eyespots on a moth's wing that can startle a hungry bird

Thorns on a plant

Many plants have brightly colored fruit and flowers

Humans have a favored birth weight, neither too small nor too large. This is

stabilizing selection

disruptive selection

artificial selection

directional selection

What is a keystone species?

the first organism that populates an area

an organism upon which the entire ecosystem depends

the first fossils found in the earliest rock strata

As temperatures in the Arctic warm, which of the following changes may occur?

Tundra will be replaced by taiga

Taiga will be replaced by tundra

Temperate forest will be replaced by taiga

Tundra will be replaced by desert

Taiga will be replaced by temperate rain forest

What is desertification?

restoration of vegetation and water to deserts

areas adjacent to deserts also become deserts

abandonment of a habitat by animals

Evolution occurs at the level of

individuals

populations

communities

The maximum population that the environment can support is called the

biotic potential

environmental resistance

carrying capacity

replacement reproduction

demographic transition

A population with relatively more pre-reproductive individuals is common in _____-developed countries

less

Endangered species sometimes breed in captivity. Why are such species endangered in the wild?

Their population density is too high

Loss of habitat

Their environment is polluted

Abiotic components of an ecosystem include

only animal life

only plant life

living components only

nonliving components only

both living and nonliving components

Carbon returns to the atmosphere

as carbon dioxide

from respiration of plants

by the burning of fossil fuels

from respiration of animals

All of the answer choices are correct

Why does the Tropical Rain Forest contain an abundance of antibiotic compounds?

The area is crowded, leading to random production of useful compounds

The area is wet. plants had to develop resistance to fungi and bacterial infections

There is a great diversity of plants, leading to random production of useful compounds

The carrying capacity of the environment for a species is determined by

the reproductive rate of the organism

the number of organisms of that species

the state and national wildlife laws pertaining to that species

a complex

the limited productivity of the environment and the environmental resistance to the biotic potential of the organism

An introduced species that breeds and spreads is

resourceful

harmful

native

dominant

invasive

What is disruptive selection?

environmental influences that select against change

environmental influences that promote one phenotype versus all others

environmental influences that promote two or more phenotypes versus all others

Natural selection acts on

individuals

populations

communities

Two populations of birds live in the same area but have different sleep/wake cycles. This is

behavorial isolation

mechanical isolation

geographical isolation

temporal isolation

An insect that resembles the face of a snake avoids predation by

camouflage

warning coloration

mimicry

chemical defense

mutualism

Unselfish acts that help others in a group so that they increase their chances of surviving and reproducing is called

imprinting

mimicry

altruism

learning

instinct

If an environment changes rapidly, organisms with ____ will be more likely to survive and reproduce.

the correct allele frequency

existing neutral mutations

existing beneficial mutations

How did geology influence Darwinâs thoughts?

It demonstrated that the earth was very old, therefore there was enough time for species to evolve

it demonstrated that all continents were similar

it demonstrated the presence of many fossils

The founder effect occurs when

large groups of individuals leave their home population and establish new settlements, mating only among themselves

many members of a population die, resulting in a great loss of genetic diversity

many members of a population reproduce causing too much genetic diversity within the population

small groups of individuals leave their home population and establish new settlements, mating only among themselves.

The greenhouse effect is due to high atmospheric

Nitrogen

Ammonia

Carbon monoxide

Carbon dioxide

Oxygen

What are the Reproductive Barriers that keep species separate?

lack of food; lack of habitat; lack of potential mates; lack of nesting sites; lack of genetic variation

mountains; canyons; glaciers; bodies of water (for terrestrial animals); areas of land (for aquatic animals)

habitat isolation; temporal isolation; behavioral isolation; mechanical isolation; gamete isolation

What is directional selection?

environmental influences that select against change

environmental influences that promote one phenotype versus all others

environmental influences that promote two or more phenotypes versus all others

Which of the following is correct when describing a predator-prey cycle?

A decline in the numbers of predators causes a decline in the number of prey

A decline in the numbers of prey causes a decline in the number of predators

An increase in the number of predators triggers an increase in the number of prey

An up-and-down cycle will be seen for the prey animal

A seasonal die-off that will occur without the other species present

Why are top-level predators (lions, eagles, humans) so rare in a community?

Only a small amount of the energy is passed from one trophic level to the next

They do not breed as fast as other animals

Because of predation by higher predators

It is difficult for them to learn how to capture prey

Their job is to keep the population size of other animals in check

Alleles conferring bright color to male guppies are common because

they make males less visible to predators

they help males identify each other

they are preferred by females

Organisms that obtain their energy from producers or other consumers are

autotroph

heterotroph

producer

autotroph and producer

heterotroph and producer

What is the environmental impact of strip mining?

lack of trees exposes the surface of the earth, promoting runoff and loss of adjacent trees

removal of minerals from the soil hampers growth of vegetation

it causes a potential increase in volcanic activity

Two populations of squirrels are separated by a mountain range and would not be capable of interbreeding. This is an example of:

behavorial isolation

mechanical isolation

geographical isolation

temporal isolation

What is a danger of overfishing?

humans will become dependent upon fish

selection for smarter fish that can avoid being caught

driving the population back into the lag phase

What is meant by prezygotic versus postzygotic speciation mechanisms?

before versus after formation of a zygote

before versus after meiosis

before versus after gamete formation

The relatively short term changes in allele frequencies within a species or population is

artificial selection

microevolution.

speciation

macroevolution

Avoidance of a location with predators is the result of

imprinting

mimicry

altruism

learning

instinct

What is the difference between Density-Dependent and Density-Independent Factors on populations?

density-dependent factors exert a greater influence when there are more individuals; density-independent exerts the same influence on all individuals regardless of their number

density-dependent factors exert a greater influence on larger, more dense individuals; density-independent factors exert the same impact on individuals of all size

density-dependent factors exert the same influence on all individuals regardless of their number; density-independent factors exert a greater influence when there are more individuals regardless of their number

All of the organisms in a given location or area is termed a

peer group

flock

community

population

herd

The concentration of the pesticide DDT would be highest in

a minnow

a mosquito larva

a seagull

plankton

algae

Our biosphere is

the Earth

the atmosphere

the ocean

land on Earth

fresh and salt water

What is meant by âcarrying capacityâ?

the amount of food produced in an ecosystem

the extent of energy required to maintain an ecosystem

the number of individuals that can be supported by an ecosystem

Species living on another is

resource partitioning

coevolution

symbiosis

predation

niche sharing

One species feeding on another is

competition

a community

an ecosystem

predation

symbiosis

Populations of different species interacting with one another in a natural environment is called

competition

a community

a biome

predation

symbiosis

Which of the following is not a biogeochemical cycle?

ATP cycle

water cycle

carbon cycle

phosphorus cycle

nitrogen cycle

Horses became larger and faster to escape predators. This is

stabilizing selection

disruptive selection

artificial selection

directional selection

Design an experimentin which you will test the effect of an acidic fluid on enzymaticactivity. (Recall: enzymes are proteins.) To complete this project,it may be useful for you to review the Scientific Method Tutorial (found the CourseContent section of the classroom under the Science Learning Centerlink) and the Scientific Method lab (Lab 1), so that you canbetter understand how to design an experiment. It may also behelpful for you to review Lab 4 (Enzymes). As you review Lab 4, youwill be reminded that there are several factors that impactenzymatic activity: pH, temperature, and amount of reagent. Feelfree to refer to observations and information from Lab 4 as youcomplete the questions required in the Final Applied Project (seethe questions below).

As you design yourexperiment for this project, please remember that you are trying toexamine how an acidic fluid will modify the outcome of an enzymaticreaction. To successfully complete this project, you will need toidentify the question(s) being asked in your experiment and thehypothesis that you are testing. In your experimental design, youmust clearly explain what you are doing. That means that you willneed to identify the enzyme and the acid, as well as explain yourexperimental protocol (this information will help you to answerquestion 2). You must alsothoroughly explain how the addition of the acidic fluid impactedthe overall reaction process (this information will help you toanswer question 4).

Hint: Keepin mind that the acid will change the environmental conditions ofthe experiment (for example, a low pH value could change the shapeof the active site on the enzyme protein), without directlyparticipating in the reaction.

please address the following:

1. What question are you asking?Clearly state your hypothesis.

2. Design an experiment. Provide adetailed account of the materials and methods used to conduct theexperiment. Also include the methods for data collection andanalysis.

3. Conduct the experiment and recordyour results below. What did you observe? Which samples showedbubbling?

4. Use your knowledge about factorsthat effect enzymatic activity to interpret your results. It may benecessary for you to refer to your lab manual and/or otherresources. What effect did the acid have on the enzyme?

5. Was your hypothesis supported? Whatis your conclusion? Explain your answer.

6. Cite all references used tocomplete your Final Applied Project.