Learn Which Sharks Lay Eggs

Bony fish produce large numbers of eggs that may scatter throughout the ocean, sometimes getting eaten by predators along the way. In contrast, sharks (which are cartilaginous fish) produce relatively few young. Sharks have a variety of reproductive strategies, although they can be divided into two main groups: those that lay eggs and those that give birth to live young. How Do Sharks Mate? All sharks mate through internal fertilization. The male inserts one or both of his claspers into the females reproductive tract and deposits sperm. During this time, the male may use his teeth to hold on to the female, so many females have scars and wounds from mating. After mating, the fertilized eggs may be laid by the mother, or they may develop either partially or fully inside the mother. The young of different species get their nourishment through a variety of means, including a yolk sac. Egg-Laying Sharks Of the approximately 400 species of sharks, about 40% lay eggs. This is called oviparity. When the eggs are laid, they are in a protective egg case (which sometimes washes up on the beach and is commonly called a mermaids purse). The egg case has tendrils that allow it to attach to a substrate such as corals, seaweed, or the ocean bottom. In some species (such as the horn shark), the egg cases are pushed into the bottom or into crevices between or under rocks. In oviparous shark species, the young get their nourishment from a yolk sac. They may take several months to hatch. In some species, the eggs stay inside the female for a period of time before they are laid, so that the young have a chance to develop more fully and thus spend less time in the vulnerable, immobile egg cases before they hatch. Types of Sharks That Lay Eggs Shark species that lay eggs include: Bamboo sharksWobbegong sharksCarpet sharksHorn (bullhead) sharksSwell sharksMany catsharks Live-Bearing Sharks About 60% of the shark species give birth to live young. This is called viviparity. In these sharks, the young remain in the mothers uterus until they are born. The viviparous shark species can be further divided into the ways the young sharks are nourished while in the mother: ovoviviparity, oophagy, and embryophagy. Ovoviviparity Some species are ovoviviparous. In these species, the eggs are not laid until they have absorbed the yolk sac, developed, and hatched, and then the female gives birth to young that look like miniature sharks. These young sharks get their nourishment from the yolk sac. This is similar to sharks that form in egg cases, but the sharks are born live. This is the most common type of development in sharks. Examples of ovoviviparous species are whale sharks, basking sharks, thresher sharks, sawfish, shortfin mako sharks, tiger sharks, lantern sharks, frilled sharks, angelsharks, and dogfish sharks. Oophagy and Embryophagy In some shark species, the young developing inside their mother get their primary nutrients not from a yolk sac, but by eating unfertilized eggs (called oophagy) or their siblings (embryophagy). Some sharks produce a large number of infertile eggs for the purpose of nourishing the developing pups. Others produce a relatively large number of fertilized eggs, but only one pup survives, as the strongest one eats the rest. Examples of species in which oophagy occurs are the white, shortfin mako, and sandtiger sharks. Viviparity There are some shark species that have a reproductive strategy similar to humans and other mammals. This is called placental viviparity and occurs in about 10% of the shark species. The eggs yolk sac becomes a placenta attached to the females uterine wall, and nutrients are transferred from the female to the pup. This type of reproduction occurs in many of the larger sharks, including bull sharks, blue sharks, lemon sharks, and hammerhead sharks. References Compagno, L. ,et al. Sharks of the World. Princeton University Press, 2005.Greven, H. Viviparous Sharks, https://www.sharkinfo.ch/SI1_00e/vivipary.html.â€Å"Shark Biology.†Ã‚  Florida Museum, 29 July 2019, https://www.floridamuseum.ufl.edu/discover-fish/sharks/shark-biology/.Skomal, G. The Shark Handbook. Cider Mill Press Book Publishers, 2008.

Texas Is A State Of The Wild Frontier - 1605 Words

Texas Texas is a state that is dearly loved by its inhabitants, and even some who do not live there. Despite how many people love it, there are a lot of people who dislike Texas and the pride Texans have for it. Texas fought for independence from a country much larger than itself, and then chose to become a part of the United States, while still reserving the right to secede. Many people do not take into accord the reasons why Texans are so proud. Perhaps the most famous Texans are men who weren’t even born in the state. David â€Å"Davy† Crockett won himself the nickname â€Å"King of the Wild Frontier† after many adventures and fighting many battles. It was said he weighed at least one-hundred-and-eighty-pounds and stood over six feet tall, and†¦show more content†¦Crockett knew of a few of President Jackson’s corrupt ways, and after calling him out on these things, President Jackson, nicknamed â€Å"Old Hickory† used his powers to keep D avy Crockett from serving a third term in Congress. Angered by this, Crockett said, â€Å"If I’m not permitted to serve my own country any longer, my constituents can go to hell, and I will go where people need me, that place being Texas† (Kubiak 87-88). This is a quote that became very popular among modern Texans after being shortened to â€Å"You may all go to hell, and I will go to Texas.† When he arrived in Texas in January of 1836 with twelve other men, he read the oath of Texas allegiance. He turned down a position of command, and stated that he wanted to defend the most defenseless part of the Alamo (Kubiak 102, 90). The first shot fired at the Battle of the Alamo was by Davy Crockett, which caused the first blood to fall. It was reported that Davy Crockett hit his target at least 300 feet away. After the Texan soldiers had been destroyed, Santa Anna sent in his men to find the leaders of the Texans. They found David Crockett amidst a room full of dead Me xican soldiers (Kubiak 91). David Crockett has since been named a hero to all Texans. Alongside Davy Crockett, there were two other men who were seen as leaders of the Texas Revolution: William B. Travis and Jim Bowie. All three of them died together during the Battle of the Alamo. Bowie, who had contracted pneumonia and typhoid, and had no

Renal System Physiology free essay sample

If the blood vessels in the kidneys are damaged, they may stop removing wastes and extra fluid from the body. The extra fluid in the blood vessels may then raise blood pressure even more. Its a dangerous cycle. 12. Briefly explain what will happen to the glomerular capillary pressure and glomerular filtration rate if both the afferent and efferent arteriole radius is decreased? Explain!!! (3 points) ? The simultaneously implementation of both arteriole rates changing caused glomerular filtration rate and low blood pressure conditions went above the baseline value. 13. How could an increased urine volume be viewed as beneficial to the body? (2 points) ? It removes toxins from the body. 14. Diuretics are often prescribed to patients with chronic high blood pressure. Why? (2 points) ? For high blood pressure, diuretics, commonly known as water pills, help your body get rid of unneeded water and salt through the urine. Getting rid of excess salt and fluid helps lower blood pressure and can make it easier for your heart to pump. We will write a custom essay sample on Renal System Physiology or any similar topic specifically for you Do Not WasteYour Time HIRE WRITER Only 13.90 / page 15. What will happen to the urine volume and concentration as the solute gradient (concentration) in the interstitial space is increased? Explain!!! (3 points) ? It increases because ADH causes water to move out of urine and the more solute there is the more concentrated the urine. 16. Speculate on ways that desert rats are able to concentrate their urine significantly more than humans? (Think: Hormones) (2 points) ? They probably produce more ADH to get all the water possible from the urine as there is not a lot of water in the desert. 17. What would be a reasonable mechanism for diuretics? (2 points) ? They act by diminishing sodium reabsorption at different sites in the nephron, thereby increasing urinary sodium and water loss. 8. What will happen to the glucose concentration in the urinary bladder as glucose carriers are added to the proximal tubule? Explain!!! (2 points) ? Glucose concentration in the urine decreased because the carriers were able to get the glucose across. 19. Predict what will happen to the urine volume (compared to normal) when aldosterone is added to the distal tubule. Explain!!! (2 points) Predict what will happen to the urine volume (compare to normal) when ADH is added to the collecting duct. Explain!!! (2 points) Urine concentration increases, and urine volume decreases because it causes the body to absorb water from the urine. Predict what will happen to the urine volume and the urine concentration (compared to normal) in the presence of both aldosterone and ADH. Explain!!! (2 points) They both have similar effects, they are agonist so adding both will decrease urine volume, and increase urine concentration. ADH increases water permeability and aldosteron reabsorbs sodium ions and water but loses potassium ions. Why does alcohol consumption lead to a dramatic increase in urine production? (2 points) Because the proximal tubule reabsorbs more water which accounts for increase urine production. Why do angiotensin converting enzyme (ACE) inhibitors given to people with hypertension lead to increased urine production. (Hint: think what ACE is doing and its effects on arterioles) (4 points) ACE inhibitors dilate blood vessels and increase the amount of water your kidneys get rid of, lowering blood pressure. 4

The study of a panda Essay Example

The study of a panda Paper The panda is black and white, like a bear in shape, but different. Things to remember in the last hour before the exam: Life processes at the cellular level (This is not a revision sheet youve done that by now Its a list of things you might want to remind yourself about 1. Cell parts. Most structures/organelles common to animal and plant cells. [P] = plants only C] Cytoplasm transparent Jelly ? cells activities occur here CLC Cell/plasma membrane regulates movement of materials in/out of cell. SELECTIVELY permeable. Phosphoric belayed. Phosphate heads (hydrophilic) face inside cell/outside cell. Fatty acid tails of lipids (hydrophobic) to interior. Small molecules e. G. Water diffuse through. Larger ones transported via protein channels. 0 Nucleus cell control centre, controls metabolism via enzymes. Contains genetic info DNA. Chromosomes only visible when cell is dividing. Contains nucleolus makes RNA and ribosome. Cell wall [P] protects cell gives strength and support. Is permeable and made of cellulose. Controls turgidity (can resist high internal pressures without stretching). 0 Chloroplasts [P] site of photosynthesis, contain chlorophyll green light-trapping pigment. Elongated shape maximizes S. A. To volume ratio, Increasing uptake of CO and H2O uptake and output of 02 and glucose (photosynthetic capacity). Chlorophyll molecules embedded In grand (stacks of ethylated membrane) more S. A. More chlorophyll = Max. Amount of light captured = more photosynthesis. Surrounded by stoma enzymes and water. 0 Large (central) vacuole [P] large and permanent structure containing cell sap (salts, sugars, amino acids). Salts in sap produce strong tendency for water to enter cell (by osmosis) keeping cell turgid. We will write a custom essay sample on The study of a panda specifically for you for only $16.38 $13.9/page Order now We will write a custom essay sample on The study of a panda specifically for you FOR ONLY $16.38 $13.9/page Hire Writer We will write a custom essay sample on The study of a panda specifically for you FOR ONLY $16.38 $13.9/page Hire Writer Vacuole displaces cytoplasm to edges of cell meaning chloroplasts are close to CO and light. Also short gas diffusion distances. 0 Mitochondria site of aerobic respiration. Enzymes attached to Cristal (membranes folded to Increase the S. A. = greater # of enzymes) produce ATOP (adenosine troposphere). Occur In high numbers In cells with large energy needs e. G. Sperm muscle cells. 0 Googol flat disc shaped sacs modify and package proteins C] ERE: Rough has bound ribosome (site of protein synthesis) makes proteins and transports proteins to Googol. Smooth has free ribosome makes steroids, lipids and hormones 2. Specialized cells perform specialized functions in multicultural organisms. Examples include: 0 Guard cells form stoma (small opening in epidermis) when turgid. Turgid = crescent moon shaped, flaccid = oval shape. Thick inner walls help them open/close stoma. Allow CO and 02 in and out. Also main route of H2O loss via transpiration. Swelling of vacuole controls opening/closing. Contain chloroplasts. 0 Palisade cells long, thin column shaped cells many can fit close together. Contain MANY chloroplasts. Cells arranged vertically so light passes through less cell walls to cells beneath. 0 Spongy mesosphere (beneath palisade layer) has more rounded not so tightly packed cells. Large Intracellular alarm spaces maximizes diffusion rate of gases during photosynthesis. (CO In 02 out). CLC Root hair cells Long and thin extension at one end with thin cell to vastly increase S. A. For absorbing small BIOLOGY Dont forget to throw this away DO NOT take it into the exam by mistake We dont want you disqualified by mistake 3. Movement. Three main mechanisms. Diffusion: Movement of substances from high concentration to low concentration along a concentration gradient which exists until diffused substance is evenly distributed. Passive movement. E. G: CO diffusing in / 02 out of leaf (through tomato). Note: can occur Just in solutions, as well as across membranes. 0 Osmosis: Movement of H2O from high concentration of H2O to a low con. Of H2O water through semi/selectively permeable membrane ( from a more dill. Solution to a more con. Solution). Passive movement. E. G. Absorbing water through plant roots, kidney tubules reabsorbing water. Active transport: Movement from a low con. To a high con. Energy is required. E. G. Absorption of MGM by roots, glucose uptake in intestines. 4. Enzymes. Protein molecules acts as biological catalysts increase rate of reactions. Substrate = molecule the enzyme acts. Increase in substrate concentration = increase in rate up to a maximum. Enzymes are specific have AD shape with unique active site only work on a particular substrate. Function best in particular conditions e. G. An optimum temperature and optimal PH. (function poorly outside these). At very low temperatures, enzyme action slow; as temp. Increases reaction rate increases (more collisions/time) BUT at high temperatures enzyme is denatured (peptide chains unravel active site is lost enzyme is permanently inactive). CIO every ICC rise enzyme activity approve.. Doubles. Co-enzymes complete the active tit essential to enzyme action. Inhibitors (poisons) combine with active site to prevent enzyme function. 5. Photosynthesis. Needs CO via stomata, H2O via roots and xylem, sunlight and chlorophyll. CHIC + AH 0 C6H1206 + 602. Sunlight needed as source of (solar) energy. Rate affected by light: more light = more photosynthesis up to point where plant is at Max. Photosynthesis level any increase in light intensity wont affect the plant further. Rate at midday >early morning [evening. No photosynthesis at night. Rate in summer > winter. Temperature affects rate. 6. (Aerobic) Respiration. C6H1206 602 0 CHIC + AH. Breakdown of glucose occurs in 2 steps glycoside in cytoplasm, then Krebs/citric acid cycle in the matrix of the mitochondria and electron transport system on Cristal of mitochondria. Energy from food (from breakdown of glucose and fatty acids) converts ADAPT + P 0 ATOP. ATOP = the energy carrier / energy in a usable form. ATOP is broken down elsewhere to ADAPT + P releasing useful energy for cellular work. 7. Cell division. 0 A cell cycles between periods of cell division, growth, normal activity (enterprise) and back to division. DNA replication occurs DNA makes exact copy of itself prior to ell division so there is a full set of genetic information available in each cell after division then preparation for mitosis then mitosis. The cycle repeats. DNA contains code for synthesis of proteins in its base sequences. All cells need the code to synthesis essential proteins for the cell to grow and carry out its role. DNA must replicate accurately so all new cells have a complete copy of the code. 0 Key steps. DNA helix unwinds, two strands unzip between bases, new nucleotides Join to the enzymes. Base pairing (A-T and C-G) essential provides mechanism accurately making two identical DNA molecules.

The French Expression àCause de (Because of)

The French Expression ' Cause de' ('Because of') cause de,  pronounced ah koz deu, is a French prepositional phrase that means because of or due to. Depending on whether the context is negative or positive, it can also be translated as: on account of, owing to or for the sake of. With Blame Essentially, cause de blames someone or something for a negative situation or event, as in:   Ã‚  Ã‚  Jai oublià © mes clà ©s cause de lappel de Philippe.   I forgot my keys because of/on account of Philippes phone call.  Ã‚  Ã‚  A cause de la mauvaise à ©conomie, jai perdu mon emploi.   Due to / owing to  the bad economy, I lost my job. Without the Blame A cause de can also be used for a neutral situation or event, something that deserves neither blame nor credit, as in:   Ã‚  Ã‚  Je lai pardonnà © cause de son à ¢ge.   I forgave him considering his age.  Ã‚  Ã‚  Il va venir la fà ªte cause de toi.   Hes going to come to the party for your sake. With Cest To say its because of/due to ... use cest in front of cause de, as in:   Ã‚  Ã‚  Cest cause de cette dà ©cision que nous nous sommes disputà ©s.   Its due to that decision that we argued. Remember the Contraction Remember that de followed by the definite article le or les must contract:   Ã‚  Ã‚  Jai paniquà © cause du bruit.   I panicked because of the noise.  Ã‚  Ã‚  Il est parti cause des enfants.   He left because of the children. An Antonym To give credit for something positive, use the expression grà ¢ce   (thanks to), as in: Grà ¢ce ton assistance, il a fini le travail.   Thanks to your help, he finished the work.Grà ¢ce aux conseils de Pierre, nous avons trouvà © la maison parfaite.   Thanks to Pierres advice, we found the perfect house.  Sil a rà ©ussi lexamen, cest grà ¢ce toi.   If he passed the test, its all thanks to you. Additional Resources Expressions with Expressions with deMost common French phrases

Dopamine and its Role in Parkinsons Disease Research Paper

Dopamine and its Role in Parkinsons Disease - Research Paper Example The researchers in this study stated that there appeared to be a link between depression and anxiety in PD.   According to Lemke, these studies proved that dopaminergic treatment for PD was important and that there was a correlation between PD and depression. 1.1 Dopamine Agonists and Depression According to Lemke, dopamine agonists work on the dopaminergic systems of the body (10). Because they work directly on these areas, they may be responsible for mood behavior. One dopamine agonist, pramipexole, was studied by other researchers and found to react as an antidepressant for bipolar disease and treatment-resistant depression (10). Several studies in this study showed that patients who took pramipexole performed better and were less depressed than those who did not take it (11). 1.2 Anhedonia and Depression Anhedonia is another agonist that has had positive effects on depression with PD patients and it has also affected any motor alterations (11). Several studies were quoted in Le mke’s article that used this agonist. All of the other studies found that patients with PD were helped via the use of agonists by controlling depression. Lemke concluded that PD patients with depression â€Å"might† benefit from a global approach to the disease that included dopamine agonists because they seemed to reduce motor complications and symptoms of depression. By using agonists the regimen of drugs could be lessened and would stop any side effects from the antidepressant medications that the patients may be taking.

Sir Richard Bramson and the Virgin Group of Companies Essay

Sir Richard Bramson and the Virgin Group of Companies - Essay Example The success of his prestigious group of companies is a confirmation of his ability to apply the necessary management skills and strategies required for successful businesses. Sir Richard Branson had no initial intentions of becoming an entrepreneur although this did not prevent him from building his status as one of the most successful entrepreneurs globally. Having launched a student magazine at the age of sixteen and managed a student advisory centre, Branson had a background in business establishment and management i.e. habitual entrepreneur (Branson, 2011; Shavinina, 2008: 9-15). However, the success and expansion of the Virgin Group led to incorporation of other business ventures making him a portfolio entrepreneur. Some of the personal entrepreneurial characteristics that have enabled Branson to emerge as an exemplary entrepreneur include his high level of motivation, high levels of self confidence, abundant energy levels and the ability to sustain the entrepreneurial approache s in long term (Branson, 2011). Additionally, he has exhibited his worth as a risk-taker, the ability to set achievable goals, innovation and a problem solver (Bolton and Thompson, 2000). He variably contributed to the entrepreneurial sector through the establishment of a brand image and identity of the Virgin Company in the global markets. The company’s marketing strategies prioritises on the customers; improving loyalty. His management skills have led to the growth of the company to international standards. The employee commitment that the company exhibits indicates that Sir Richard Branson possesses effective employee management skills that keep employees always motivated. The dedicated and united employee team has utilised the business and marketing strategies associated with the business to constantly enable the business improve performance. Application of these strategies in all marketing segments has enhanced the application of innovation in all marketing segments. Ana lysis of the Virgin Group of companies exemplifies the entrepreneurial characteristics of Branson. Entrepreneurship can be defined as a process whereby individuals or group of individuals apply organised efforts in the pursuance of opportunities (Kuratko and Hodgetts, 2004). An entrepreneur should target to create value and growth through innovation and maintenance of uniqueness. This has been the main factors that have enabled Virgin Group of companies to be successful since its establishment. According to Shavinina (2008), the formation and management of the affiliate companies of the Virgin Group exhibits adherence to the entrepreneurial process. The initial stage of the process involves the exploration of the entrepreneurial context. For instance, the establishment of Virgin Airlines was Branson’s attempt to offer reasonable freight charges for transatlantic flights. The second stage involves identification of the possible opportunities that guarantees competitive advanta ge. The venture is then established once the opportunities are identified paving way to management once all its structures are in place. According to Carmichael (2006), Branson’s skills portrays him as a transformational entrepreneur due to his insistence on maintaining Virgin Group of companies as an organisation characterised by informality and