The basic reason why unripe fruits have defensive chemicals is that they need to protect the seeds that are not ready to germinate. On the other hand, the seeds of the ripe fruits are ready to germinate and so they need to get spread with the help of animals and birds and so there are no defensive chemicals. These seeds spread to different places and the soils help them to germinate under suitable conditions.
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Carrying capacity is the maximum amount of organisms that an ecosystem can support. So to ensure that an ecosystem stays balanced the population needs to be under the carrying capacity. If it is not, then organisms will begin to die until the ecosystem is balanced again. The carrying capacity is related to limiting factors as such food, space, water, and sunlight. There are limited amounts of all of these, and they can only support so many plants and animals.
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Organisms are part of both the carbon cycle and the water cycle.
The water cycle tracks water and the carbon cycle tracks carbon.
Explanation:
Answer:
reduced thrombogenicity.
Explanation:
For patients with significant heart valve disease, surgical options for treatment include valve repair or replacement. The choice between repair and replacement is influenced by a number of factors including age, type of the valve disease and other medical conditions. When valve replacement is performed, there are options of mechanical or tissue heart valves. These two classes of valves confer different characteristics and each have their advantages and disadvantages.
Mechanical valves: Mechanical heart valves are made from materials such as titanium and carbon. They usually consist of two leaflets and a metal ring surrounded by a ring of knitted fabric, which is sewn onto the heart in place of the original valve.The main advantage of mechanical valves is that they are very durable. However, these valves provide a surface on which blood clots can form easily. As a result, anyone who has been implanted with a mechanical valve needs to be on lifelong blood-thinning medication, such as warfarin, to prevent the development of blood clots that can cause heart attack or stroke
Tissue valves, also known as biological or bioprosthetic valves, are composed of animal or human tissue. The valves are derived from animal tissue such as porcine (pig), bovine (cow) and equine (horse) models, and then fixed with a preserving solution that may be mounted on a flexible frame to assist in deployment during surgery. As with mechanical valves, the bottom of a tissue valve is often surrounded by a ring of knitted fabric that is sewn onto the heart. In addition to animal-derived valves, a human tissue valve from a donor human heart, known as an allograft or homograft, may also be used as a replacement valve. Tissue valves can be used in open heart surgery or in a minimally invasive aortic operation known as transcatheter aortic valve implantation (TAVI).
Advantages of tissue valves compared to mechanical valves include the avoidance of lifelong warfarin therapy to prevent the development of blood clots.
The scientist that disproved the idea that life comes from non-life was <em>Luis Pasteur</em><em />
The scientist who tried to prove that life comes from non-life was John Needham. To do this, he took an open flask and put broth in it, heated it up, then sealed it, finding signs of life in it days later. He used that experiment to try and prove that life could come from non-living things.
Luis Pasteur disproved this theory by placing broth in a swan-necked flask, so that it was open to air and bacteria, and heating it up to sterilize it. After a few days the broth did not have any signs of life in it, but if the neck was cut off, then within a few days the broth began to mold and bacteria started growing. This proved that spontaneous generation does not occur, otherwise the broth in the swan-necked flask would have molded over as well.
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