BIOLOGY MIDTERM ESSAY
1. How does the biologist determine whether a thing is living or nonliving? Or what characteristics do living organisms have that non-living things do not? They look at it under a microscope and see if it has cells. Basically, if it has cells the it's alive. If it doesn't have cells it is considered nonliving. There are smaller archaebacteria that behave like small parts of cells. These are considered living too, because they have chemical bonds of RNA, which is the singular shorter form of DNA. There is evidence that viruses change with different hosts, but they are generally considered non-living. They are much smaller chemical chains (with some form of movement and reproduction) and do not come from cells through reproduction. They come from cells by 'hijacking' normal cells and inserting their small chemical chains into the cells' DNA or RNA. The cells and all its organic machines change to function like the virus and eventually collapse to spread the virus. If that's living, it sure beats staying inside typing so many hours with a cold. Viruses are not complex enough to really change their movements or transmissions. They are like cancer in that they are cellular malfunctions, except they transmit to other hosts. They do change slightly, but biologists do not qualify this change as a property of life: they just look for cells. 2. State the significance of photosynthesis and cellular respiration to all life. Describe three differences that exist between these two chemical processes. Photosynthesis is the main process on Earth that traps energy in food molecules. Cellular respiration breaks the bonds in the food molecules to put energy into a form that the cells can use directly.
1. Photosynthesis requires water and carbon dioxide; respiration requires glucose and oxygen. 2. Photosynthesis produces oxygen and glucose; respiration produces carbon dioxide and water. 3. Photosynthesis builds glucose to store energy; respiration breaks glucose to release energy. 4. Photosynthesis happens in the chloroplasts; respiration happens in the mitochondria. 5. Only autotrophs carry on photosynthesis; all living things carry on respiration. 3. Distinquish between red blood cells, white blood cells, and platelets. What are their functions? Red blood cells carry oxygen and nutrients to the cells and carry away wastes and carbon dioxide. White blood cells are a defensive mechanism designed to defend the body from invaders. Platelets are designed to heal wounds by coagulating the blood and forming scabs at the wound site. (1) Functions:
a- Red blood cells (RBCs) = Transfer of oxygen from lungs to different body organs and tissues. b- White blood cells (WBCs): Defense mechanism against invading microorganism (phagocytosis). c- Platelets = Blood agglutination during injury.
1- Size : Platelets = small (2 micrometers). RBCS = 5 micrometers. WBCs = large up to 50. 2- Shape: THE SAME ORDER: irregular, rounded, rounded but can change shape while moving. 3- Structure: one unit, empty no visible structure, neuceated some have granules.
4- Numbers: RBCs come first followed by platelets then WBCs.
4. Identify 3 important reasons why cells use energy. Include glucose, glycolysis, and ATP. To build up needed proteins
to maintain active transport (ATP) to keep concentration constant to transport via filaments molecules to where they are needed all 3 process use ATP
ATP comes from the breakdown of glucose by glycolisis
5. Describe the principles of dominance, segregation, and independent assortment, based on Mendel's experiments. Independent assortment is a basic principle of genetics developed by a monk named Gregor Mendel in the 1860's. Mendel formulated this principle after discovering another principle now known as Mendel's law of segregation. This principle states that the alleles for a trait separate when gametes are formed. These allele pairs are then randomly...
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