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limeyak247Lv1

29 Sep 2019

You are standing at the bottom of a deep canyon in East Africa. While looking at the canyon walls, you notice that there are fairly distinctive layers of soil and rock. In a layer at about your knee level you see a skull (#1) with big teeth and a small cranium (and therefore a small brain). You look upward and in a different layer that is at about eye level you see another skull (#2). It is very similar to the first, but you notice some differences. The teeth are smaller but the cranium is larger. Given this information, answer the following three questions.

1. Which skull is older, #1 or #2?

2. Is that assessment based on relative dating or chronometric dating? Which specific technique is utilized?

3. If you infer that the two skulls are so similar that they are related, but different enough to be different species, does this represent microevolution or macroevolution?

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Bunny GreenfelderLv2

29 Sep 2019

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Itâs Friday morning and Sal Volpe is sitting in Dr. Lorraineâs exam room, dozing after another night of disrupted sleep. When the doctor knocks and walks in, she finds the 66-year-old man looking exhausted and uncomfortable. Sal gets to the reason for his visit immediately: Heâs been suffering from âstomach achesâ (dyspepsia) that wake him at night and nag him in between meals during the day. He describes his pain as gnawing, burning (maybe a 4 out of 10 on a pain scale) and points to the epigastric region of his abdomen. When he eats, he tells Dr. Lorraine, the pain goes away, but then he feels bloated and a little nauseated. The pain usually returns 2â4 hours later, depending on what he eats. Sal explains that he has had some pain relief from the over-the-counter drug PepcidÂ® (famotadine).

Dr. Lorraine proceeds with the history and physical exam. She discovers that Sal has a family history for gastrointestinal cancer and has unintentionally lost 10 pounds since his checkup a year ago. His epigastric area is modestly tender to palpation. She suspects a peptic ulcer (gastric or duodenal), but the weight loss and family history make it prudent to eliminate the diagnosis of stomach (gastric) cancer. âMr. Volpe, I think you may have a stomach or intestinal ulcer,â Dr. Lorraine says. âI suggest we perform an endoscopy to have a look. This involves passing a small tube with a small camera through your mouth and into your stomach. We can look at the wall of your stomach and small intestine, check for an ulcer, and remove a very small piece of tissue to test for infection. We call this a biopsy. Weâll also test the biopsy for cancer because of your family history. But, I really think weâre dealing with an ulcer here and not cancer.â

Later that month, the endoscopy is performed and it confirms Dr. Lorraineâs suspicions. Sal has a duodenal ulcer and infection with the bacterium Helicobacter pylori (H. pylori). This is not surprising since H. pylori is the cause of most peptic ulcer disease, particularly in the duodenum. Treatment involves complete eradication of the H. pylori with two different antibiotics, and a drug that decreases gastric acid secretion, a so-called proton pump inhibitor (PPI). Dr. Lorraine explains to Sal, âMr. Volpe, you do not have stomach cancer, but you do have a duodenal ulcer caused by the H. pylori bacteria I was telling you about. Too much acid and inflammation from this infection is causing your pain. The good news is we can probably cure your ulcer by killing the bacteria, but you will have to take three different medications twice a day for 14 days. Iâll see you again in 3 weeks; we can do a simple breath test to determine if the H. pylori has been successfully eliminated.â

Short Answer Questions:

The structures in the epigastric region share a common nerve supply. Can you name the specific cranial nerve that serves this region and the part of the nervous system to which it belongs?

In order to understand the disease in Mr. Volpeâs alimentary canal, one must know the layers that make up its walls. Design a chart that identifies the four basic layers of the alimentary canal, the tissues that make up each layer, and the general function of each layer.

Dr. Lorraine suspects a peptic ulcer. This is an inflammatory lesion in the stomach or duodenal mucosa, which may extend through all layers of the alimentary canal wall. Describe the basic histological (tissue) structure of the mucosa layer in the alimentary canal. Identify the unique features of the mucosa in the stomach and in the duodenum, and explain how this uniqueness determines the function of the stomach and the duodenum.

Mr. Volpe asks, âWhat do the bacteria have to do with the ulcer?â Dr. Lorraine tells him that the H. pylori increases stomach acid secretion and, at the same time, breaks down the lining of your stomach and duodenum. What is the source and normal function of acid in the stomach and what regulates its production

Why is Mr. Volpeâs dyspepsia relieved by food, and aggravated 2â4 hours after a meal?

coffeesheep473

1. Humans have the scientific name Homo sapiens. We are members of the family Pongidae, in the order Primates, in the class Mammalia, in the phylum Chordata. Based only on this information, which of the following is not a correct statement?

a. The speciation event (lineage-splitting) that generated the genus Homo occurred earlier than the speciation event that generated the species H. sapiens.

b. The most inclusive of these taxonomic groups is Chordata.

c. The genus Homo might have as many species as are in the entire family Pongidae.

d. There can be no other species in the genus Homo.

e. All mammals must be Chordates.

2. Endotherms differ from ectotherms in that:

a. Environmental temperature has little effect on the energy budget of endotherms but a strong effect on the energy budget of ectotherms.

b. An endotherm's metabolic rate is not affected by temperature whereas the metabolism of an ectotherm has a Q10 of 2-3.

c. Endotherms are vertebrates and ectotherms are invertebrates.

d. On average, endotherms are much better sprinters (i.e., can run faster for short distances) than ectotherms.

e. Endotherms are much better able to support endurance exercise than ectotherms.

3. You measure oxygen consumption of a lizard at three temperatures, as follows: 18 Â°C: 0.090 ml O2/min 23 Â°C: 0.135 ml O2/min 28 Â°C: 0.200 ml O2/min From these data you calculate the Q10 to be:

a. 1.8

b. 2.0

c. 2.2

d. 2.5

e. none of these are correct.

4. What is the best description of how evolution by selection (natural or artificial) works?

a. mutation generates variation randomly, sex makes new combinations of genes randomly, and selection picks the best ones for reproduction.

b. selection leads to non-random mutation to make useful new alleles, which are then combined by sex.

c. exposure to environmental factors leads to non-random mutations that improve fitness.

d. through selection, mutations occur in those genes that will improve fitness.

e. mutation generates random new alleles, and sex combines them in ways that select the best for future generations.

5. Which of the following is a correct match between a major lineage and its characteristics?

a. Archaea: extremophiles, ribosomes, RNA as genetic material, no nuclear membrane

b. Eukarya: mitochondria, DNA as genetic material, photosynthetic or chemohetrotrophic

c. Bacteria: mitochondria, DNA as genetic material, no nuclear membrane

d. Eumetazoa: extremophiles, ribosomes, DNA as genetic material, nuclear membrane, chemoheterotrophic

e. Protostomes: triploblastic, eucoelomate, blastopore becomes anus, indeterminate cleavage

6. Which of the following statements about animal life history events is correct?

a. Being multicellular requires a larval stage in the life cycle.

b. Mutation is sufficient to produce considerable genetic variation between different tissues in an individual.

c. Senescence is defined by slow, constant decline in survival as individuals get older.

d. Different cell types are formed when different but specific portions of the zygoteâs DNA are lost from the different germ layers during development.

e. In an individual, the only cells that differ genetically from other cells are gametes.

7. Which of the following statements about terrestrial vertebrates is correct?

a. Jaws evolved from paired appendages, which in turn evolved because they improved swimming ability.

b. Legs evolved from fins after early fishlike vertebrates invaded the land.

c. Jaws and inner ear bones evolved from gill arches, and leglike appendages evolved under selection for aquatic locomotion.

d. Viviparity (giving birth to well-developed young instead of laying eggs) was vital to the ability to reproduce on land without returning to the water.

e. Lungs for breathing air evolved after early fishlike vertebrates invaded the land (the first land vertebrates had to depend on gills for breathing air)

8. The essential features of a hydrostatic skeleton include:

a. antagonistic muscles.

b. a non-deformable fluid-filled space

c. flexible joints.

d. compressible material capable of changing volume

e. all of the above (a) â (d) are correct.

9. You are a Peace Corps volunteer physician in a developing country. You notice that some of the villages you visit have a high incidence of a parasitic disease, but other nearby villages are unaffected. Investigating you find the villages with disease are in wet areas with lots of snails and frogs, while the disease-free villages are in drier places but have lots of insects and mice. From this information, what might you reasonably conclude about the type of parasite responsible for the disease?

a. Itâs a trematode (these need mollusks as intermediate hosts).

b. Itâs a nematode (these are vectored mainly by frogs).

c. Itâs an apicomplexan parasite (these require wet areas and enter the skin through standing water).

d. Itâs a trypanosome (these are transmitted by mammal bites).

e. The information doesnât provide useful clues about the type of parasite.

10. Which of the following pairs of primary diagnostic characters is correctly matched with taxonomic groups?

a. circulatory system vs. water vascular system: Nematoda vs. Echinodermata

b. schizocoely vs. enterocoely: Radiata vs. Bilateria

c. pharyngeal slits vs. polyp and medusa: Chordata vs. Cnidaria

d. gastrovascular cavity vs. complete gut: Cnidaria vs. Cestoda

e. hemocoel vs. contractile vacuole: apicomplexans vs. rhizopoda

Please provide explanation too.

Exercise #5: The Nervous system and Perception

Task #1: Color vision

Introduction

In the human retina, there are two kinds of light-sensitive cells: rods and cones. These cells are located on the outside of the retina, away from the vitreous humor and against the choroid layer, and are covered by a later of bipolar and ganglion cells as well as neurons. Light enters the posterior chamber through the lens and must pass through several cell layers before it is absorbed by the rods and cones.

Cones are involved in color vision at daylight intensities. Generator potentials in a cone excite one neuron, giving high-level resolution vision. Cones will not cause neural firing at low light intensities and are, therefore, nonfunctional at night.

Rods provoke black-and-white vision at low light intensities. A bipolar cell associates with several rods, so that generator potentials sum in their effect. This assures neuronal firing at low light intensities and provides a highly sensitive vision but with less resolution.

Receptor convergence. A ganglion cell, which receives input from a number of rods, spread out over the retina, cannot pinpoint the source of a light stimulus as well as a ganglion cell, which is stimulated by a single photoreceptor. In the case of a ganglion cell receiving the added input of several rods, light hitting any one of the rods can cause a neural spike in the ganglion cell, but the brain has no way to know which rod was excited. It is therefore harder to pinpoint the location of light stimuli on the retina when the stimulus is detected by rods (as compared to cones). The result is that our ability to see detail, or our resolving power, is considerably lower under dim light conditions than under bright light conditions.

Dark adaptation. If you go from a lighted area to a very dark room, you will not be able to see. After about ten minutes, however, you begin to be able to see again. This occurs because the rhodopsin pigment, which gets broken down when it absorbs light, is continually re-synthesized in the rods. When there is very little light, very little rhodopsin gets broken down and the amount of rhodopsin gradually builds up, making the rod much more sensitive to dim light.

When light strikes a receptor cell, it triggers a photo-chemical reaction that leads to neuronal firing. If a rod or cone receives high-intensity light, the visual pigments will be temporarily bleached and will not absorb any more light. Within a matter of a few seconds, enzyme systems in the cells will restore the visual pigment to its light-absorbing form. This can be easily demonstrated. If, after viewing a bright light, the eye is quickly shut or turned to a dark wall, the bright image will persist as a positive afterimage because the high generator potential causes the continued firing of neurons. If the eye is cast on a lighter background after a few seconds, a negative afterimage, or a dark image of the object will appear. This is because the still bleached cells are not receptive to the light coming from the light background.

According to the Young-Helmholtz theory of color vision, there are three types of cone cells, which respond respectively to red, green, and blue light.

All other colors are perceived as the brain interprets impulses coming from a mix of these receptors. If an object of one color is viewed for a long period of time at high light intensity, the cones for that color will become bleached. The afterimage of the object will be seen in the complementary color.

The Exercise 6 PowerPoint will demonstrate afterimages to you. Use the slide show option to project the square of red light on your entire screen in a dark room. After staring intensely at the square for 30 seconds or so, without shifting your gaze, click enter to change the slide to a soft white. Continue staring at the screen as the change is made. What do you see? What was the color of the afterimage?

Repeat this experiment using a blue square. Before doing the experiment, hypothesize what color the afterimage will be according to the Young-Helmholtz theory.

Hypothesis to be tested: (2 pts)

What did you see when the experiment was conducted? (2 pts)

Was you hypotheses accepted or rejected? (1 pt)

Explain the colors seen in these afterimages using the Young-Helmholtz theory. (5 pts)