Biology Living and Non-Living Things Essay

Pages: 7 (2149 words)  ·  Bibliography Sources: 1+  ·  Level: College Senior  ·  Topic: Biology

Biology

Living and Non-Living Things. Biology is the study of living things. Biologists are scientists who specialize in the study. They discovered more than a million life forms on earth, some of them living and some are not (Buckley 2003). They distinguish living things from non-living according to certain characteristics. These are nutrition, respiration, excretion, reproduction, growth, sensation, movement, transport, secretion, metabolism and regulation (Buckley). Other scientists recognize a living thing when it is composed of cells, requires energy to function and survive, display a hereditary pattern, responds to the environment, maintains homeostasis, and evolves and adapts (ThinkQuest Team 2000).

Nutrition means that living things eat to stay alive (Buckley 2003). Plants use energy from light to produce their food, while animals feed on plants or other animals. Respiration means that living things must breathe in oxygen to produce energy and function. Plants breathe in carbon dioxide and breathe out oxygen for use by animals. Excretion means that they eliminate matter, which they do not need. Examples are sweat, urine and feces. Reproduction means that living things reproduce their own kind or offspring like themselves. Growth means that they become bigger as they grow older. Sensation means that they perceive and react to stimuli in the environment, such as sound and light. Movement means that most living thinks change location or position. Most animals can move easily. Plants move in the direction of light. Transport means that living things must move things inside the cell or organism. Secretion means living things release specialized substances, like oils, hormones and enzymes. Metabolism refers to energy processes within a living thing or organism, which sustain its life. And regulation refers to internal balance within the organism in spite of internal and external changes (Buckley).

Other scientists believe that living things possess seven characteristics, which distinguish them from non-living things (ThinkQuest Team 2000). Living things or organisms are made up of cells, need energy to survive, reproduce their own kind, display hereditary patterns, respond to stimuli in the environment, maintain homeostasis or balance, and evolve and adapt to the demands of survival (ThinkQuest Team).

Non-living things do not possess these characteristics.

Photosynthesis and Cellular Respiration.

Some animals feed on other animals but other animals feed on plants (Alberts, et al.

2002). Plants trap energy directly from the sun to produce its food through photosynthesis. They use that energy to build atoms, which convert into proteins, nucleic acids, polysaccharides and lipids. These substances are later taken in by animals that eat these plants. Photosynthesis occurs in two stages. In the first, plants capture the sun's energy and store it as chemical bond energy in small molecules. These molecules act as carriers of energy. As a result, they give off molecular oxygen as a waste product. In the second stage, these carriers help produce sugars from carbon dioxide and water as a useful source of energy for both the plants and the animals, which later eat them (Alberts, et al.).

Energy is stored in all animals and plants in whatever form it is ingested (Alberts, et al. 2002). This energy is extracted in a usable form by living organisms through gradual oxidation or controlled burning. A vast amount of oxygen is present in the earth's atmosphere. The most energetically stable form of carbon is CO_2, while hydrogen's is as H_2O. A living cell gets energy from sugars or other organic molecules through cellular respiration. This process occurs when the cell allows its carbon and hydrogen atoms to combine with oxygen to produce CO_2 and H_2O (Alberts, et al.).

Photosynthesis and cellular respiration complement each other (Alberts, et al. 2002). Almost all living things or organisms breathe in the oxygen released by plants by photosynthesis. Animals, in turn, release carbon dioxide, which plants need to make their food by photosynthesis. This pattern shows the symbiosis among living organisms in the biosphere (Alberts, et al.).

White Blood Cells, Red Blood Cells and Platelets

Red blood cells or RBC account for almost 45% of the total volume of blood (Smith 2009). Their main function is to bring oxygen from the lungs to every cell in the body RBCs consist mainly of hemoglobin, which takes oxygen molecules from the lungs. Hemoglobin gives the blood its red color (Smith).

White blood cells or WBC comprise only about 1% of the blood volume (Smith 2009). Despite their diminutive number, they play a very important role. They are the immune system's primary defense against harmful microorganisms, such as bacteria, viruses, fungi and parasites. WBCs do this by directly attacking a perceived invader. They first identify it as foreign, attach themselves to it and then destroy it. The process is called phagocytosis.

WBCs perform this prime function by producing antibodies and releasing these into the blood (Smith 2009). An antibody attaches itself to the invader and destroy it or secure help from other cells in the immune system. The many types of WBCs include neutrophils, monocytes and lymphocytes. They interact among themselves and with plasma proteins or merge to make up a complex but very efficient immune system (Smith).

Platelets are the tiniest cells in the blood (Smith 2009). Their major function is to form clot whenever a blood vessel is broken. This process is called coagulation. Right after an injury, platelets in the area cleave and stick to the edges of the injury. They also activate a mechanism in response to the damage. This consists of constricting the blood vessels to reduce bleeding, bring in more platelets to the damage area, and trigger the plasma-based clotting components, such as fibrinogen. Fibrinogen turns into long, sticky threats of fibrin. Platelets and the fibrin join to create a mesh and a stable clot. This function of the blood is all-important to the body's survival (Smith).

Why Cells Use Energy

Cells use energy mainly to perform various chemical reactions; produce new molecules, such as enzymes; and maintain homeostasis (Alberts, et al. 2002). Through the process of cellular respiration, they break down food to produce energy in the form of adenosine triphosphate or ATP molecules (Taylor 2002). Sugars produced by plants through photosynthesis are broken down during the process. The main stages of this process are glycolysis, Krebs Cycle, and the Electron Transport Chain or ETC (Taylor).

In the glycolysis stage, glucose molecules from carbohydrates are broken down into molecules of pyruvate, which connects to the second stage (Taylor 2002). Phosphate is drawn from ATP to the glucose molecule, increasing chemical reactions. Following more steps and catalyzed by different enzymes, the phosphates are removed. The pyruvate molecules are ready for the next stage (Taylor).

In the Krebs Cycle, enzymes completely oxidize the molecules (Taylor 2002). Unlike the first stage, this stage requires the presence of oxygen to operate. It must operate twice to produce certain number of certain molecules (Taylor).

The ETC chain of electron-carrying proteins within the inner membrane of the mitochondrion of the cell (Taylor 2002). Most of the energy produced in the first two stages will be released by this chain and oxidative phosphorylation. But the chain only produces a gradient in creating ATP through chemiosmosis (Taylor).

Mendel -- Gregor Johann Mendel was an Augustinian monk who established the principles of hereditary transmission of physical characteristics (Microsoft Encarta 2009). He used garden peas in experimenting with hereditary units he called "factors" but are now called genes. Genes explain dominant or recessive characteristics (Microsoft Encarta).

Under his first principle or law of segregation, genes occur in pairs in most body cells but segregate in forming sex cells (Microsoft Encarta 2009). Sex cells are eggs or sperms. When an egg and sperm unite, they form a gene pair wherein the dominant gene renders the recessive gene passive. Mendel later found that interbreeding would produce a ratio of three to one in the second generation (Microsoft Encarta).

His continued experiments revealed that hereditary units among self-pollinated breeds did not blend but persist from one generation to another at a ratio of three-to-one (Microsoft Encarta 2009). From these findings, he established the second principle, the law of independent assortment. This states that any single characteristic of a gene is not usually influenced by that of another characteristic. These laws still form the basis of the study of modern genetics and heredity (Microsoft Encarta).

DNA and RNA - Deoxyribonucleic acid or DNA is the most important molecule in life (Ridley 2009). It is the framework and mechanism of biological inheritance in virtually all living organisms. It is present in almost all cells in the form of coded instructions, which control all their workings. It passes from parents to their offspring who develop according to these coded instructions. Its discovery is considered the most important in biological studies in the last century (Ridley).

DNA is perceived to be a long series of letters, representing two long and complementary chains of nucleotides (Ridley 2009). A nucleotide contains one deoxyribose-phosphate like and one base. The four kinds of base make four kinds of nucleotide. The letters a, C, G, and T. stand… [END OF PREVIEW]

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