Living Environment Regents Review Practice Homeostasis Question 1
Saturday, 27 June 2009 10:51
What usually results when an organism fails to maintain homeostasis?
A)Growth rates within organs become equal.
B)The organism becomes ill or may die.
C)The water balance in the tissues of the organism stabilizes.
D)A constant sugar supply for the cells is stopped.
Correct Answer: Option B - The organism becomes ill or may die.
The state of homeostasis is very important for the body. All the chemical reactions and the metabolic processes are carried otu perfectly if homeostasis is maintained. The disturbance in the homeostasis invites the diseases. The body feels weak and pale. Every organism will lose efficiency in its control systems. The inefficiencies gradually result in an unstable internal environment that increases the risk for illness. In addition, homeostatic imbalance is also responsible for the physical changes associated with aging. Even more serious than illness and other characteristics of aging, is death. Heart failure has been seen where nominal negative feedback mechanisms become overwhelmed and destructive positive feedback mechanisms then take over
By the definition on homeostasis, the rest of the options are incorrect
Living Environment Regents Review Practice Homeostasis Question 2
Saturday, 27 June 2009 11:02
Hydrogen peroxide (H2O2) is a toxic by-product of cellular metabolism in aerobic organisms. The reaction where H2O2 breaks into water and oxygen, occurs within the cells to prevent the accumulation of hydrogen peroxide the catalase functions as an:
A)Enzyme in the synthesis of hydrogen peroxide
B)Emulsifier in the digestion of hydrogen peroxide
C)Indicator in the detection of hydrogen peroxide
D)Enzyme in the breakdown of hydrogen peroxide
Correct Answer: Option D - Enzyme in the breakdown of hydrogen peroxide
Enzymes often end in -ase. An enzyme is a biological catalyst. A catalyst is a molecule which speeds up a chemical reaction, but remains unchanged itself. Each type of enzyme will usually act upon one type of substrate molecule. In this case the enzyme catalase works only on hydrogen peroxide (H2O2). An enzyme may catalyse a reaction, which causes the substrate to split, or may join two molecules together. Catalase will split the hydrogen peroxide molecule into water and oxygen and this occurs at a turnover rate of 10^7 molecules per second.
The Breakdown of hydrogen peroxide using catalase introduction enzymes such as Catalase are protein molecules, which are found in living cells. They are used to speed up specific reaction within the cell. They are all very specific as each enzyme just performs one particular reaction. Catalase is an enzyme found in food such as potato and liver. It is used for removing Hydrogen Peroxide from cells. Hydrogen Peroxide is the poisonous by-product of metabolism; this compound can kill cells. Catalase speeds up the decomposition of Hydrogen Peroxide into water and oxygen because the shape of its active site matches the shape of hydrogen peroxide molecule. This type of reaction where a molecule is broken down into smaller pieces is called a catabolic reaction. This is the reaction equation for the breakdown of hydrogen peroxide into water and oxygen.
Living Environment Regents Review Practice Homeostasis Question 3
Saturday, 27 June 2009 12:11
Which disease damages the human immune system, leaving the body open to certain infectious agents?
Correct Answer: Option A – AIDS
Acquired immune deficiency syndrome or acquired immunodeficiency syndrome (AIDS) is a disease of the human immune system caused by the human immunodeficiency virus. This condition progressively reduces the effectiveness of the immune system and leaves individuals susceptible to opportunistic infections and tumors. HIV is transmitted through direct contact of a mucous membrane or the bloodstream with a bodily fluid containing HIV, such as blood, semen, vaginal fluid, preseminal fluid, and breast milk.
Chickenpox is a highly contagious illness caused by primary infection with varicella zoster virus (VZV). It generally starts with a vesicular skin rash appearing in two or three waves, mainly on the body and head rather than the hands and becoming itchy raw pockmarks, small open sores which heal mostly without scarring.
Influenza, commonly referred to as the flu, is an infectious disease caused by RNA viruses of the family Orthomyxoviridae (the influenza viruses), that affects birds and mammals.
Pneumonia is an inflammatory illness of the lung. Frequently, it is described as lung parenchyma/alveolar inflammation and abnormal alveolar filling with fluid.
Living Environment Regents Review Practice Homeostasis Question 4
Saturday, 27 June 2009 12:15
Which process provides most of the oxygen found in Earth's atmosphere?
Correct Answer: Option C – Photosynthesis
Photosynthesis is the process of making organic food (glucose) by combining the hydrogen from water with carbon dioxide. The oxygen from splitting water is released into the atmosphere. Aerobic respiration takes in the oxygen from the atmosphere, dehydration synthesis is a mechanism of building up molecules by removing water, not oxygen, and fermentation is a form of anaerobic respiration which is done in the absence of oxygen.
Dehydration synthesis is a chemical reaction in which one or more molecules of water are removed from the reactants to form a new product. These reactions can occur when one of the reactants has a hydroxyl group (OH) that can be cleaved, thus forming the negatively charged hydroxide ion (OH -). The other reactant must have a hydrogen atom which can be cleaved to yield a hydrogen, or hydronium, ion (H+). In solution, these ions are free to combine and form a water molecule. The respective reactants are then able to form a chemical bond that creates a new compound.
Cellular respiration is the set of the metabolic reactions and processes that take place in organisms' cells to convert biochemical energy from nutrients into adenosine triphosphate (ATP), and then release waste products. Aerobic respiration requires oxygen in order to generate energy (ATP). It is the preferred method of pyruvate breakdown from glycolysis and requires that pyruvate enter the mitochondrion in order to be fully oxidized by the Krebs cycle.
Fermentation is the process of energy production in a cell under anaerobic conditions (without oxygen)
Living Environment Regents Review Practice Homeostasis Question 5
Saturday, 27 June 2009 12:16
Which activity is not a response of human white blood cells to pathogens?
A)Engulfing and destroying bacteria
C)Identifying invaders for destruction
D)Removing carbon dioxide
Correct Answer: Option D - Removing carbon dioxide
Bacteria, viruses, and any other thing that may cause disease are called pathogens. There is a variety of colorless blood cells which make the white blood cells, or known as leukocytes. These white blood cells are defenders for the body. They protect the body from bacteria and viruses, which are disease-causing organisms. Unlike red blood cells, the white blood cells contain a nucleus and are larger than the red blood cells. There are fewer white blood cells than white, but there are still about 60 billion in an adult human body. The bone marrow and lymphatic tissue produce approximately A million white blood cells every second. The white bloods cells are distribute themselves throughout the body by moving through the circulatory system. When there is an infection within the body, the white blood cells collect in the infected area and attack the foreign organisms.
Living Environment Regents Review Practice Homeostasis Question 6
Saturday, 27 June 2009 12:17
The energy an organism requires to transport materials and eliminate wastes is obtained directly from
Correct Answer: Option D – ATP
Adenosine-triphosphate (ATP) is a multifunctional nucleotide, and plays an important role in cell biology as a coenzyme that is the "molecular unit of currency" of intracellular energy transfer.In this role, ATP transports chemical energy within cells for metabolism. It is produced as an energy source during the processes of photosynthesis and cellular respiration and consumed by many enzymes and a multitude of cellular processes including biosynthetic reactions, motility and cell division. The energy from ATP is then used by the organism to obtain, transform, and transport materials, and to eliminate wastes.
Deoxyribonucleic acid (DNA) is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms and some viruses. The main role of DNA molecules is the long-term storage of information. DNA is often compared to a set of blueprints or a recipe, or a code, since it contains the instructions needed to construct other components of cells, such as proteins and RNA molecules. The DNA segments that carry this genetic information are called genes, but other DNA sequences have structural purposes, or are involved in regulating the use of this genetic information.
Hormones are chemicals released by cells that affect cells in other parts of the body. Only a small amount of hormone is required to alter cell metabolism. It is essentially a chemical messenger that transports a signal from one cell to another. All multicellular organisms produce hormones; plant hormones are also called phytohormones. Hormones in animals are often transported in the blood.
Starch or amylum is a polysaccharide carbohydrate consisting of a large number of glucose units joined together by glycosidic bonds. Starch is produced by all green plants as an energy store and is a major food source for humans.
Living Environment Regents Review Practice Homeostasis Question 7
Saturday, 27 June 2009 12:19
A drastic change in the metabolic rate of a human would most likely result from the
A)Over secretion of the salivary glands
B)Overproduction of auxins
C)Deterioration of the skeletal system
D)Malfunction of the endocrine glands
Correct Answer: Option D - Malfunction of the endocrine glands
The thyroid gland, located in the neck, is an endocrine gland that secretes hormones directly into the bloodstream. The hormone thyroxine regulates the rate of metabolism, or how fast or slow you perform life functions. Salivary glands produce enzymes to break down carbohydrates, auxins are the names of plant hormones, and the skeletal system allows us to move.
Rest options are incorrect based on above argument.
Living Environment Regents Review Practice Homeostasis Question 8
Saturday, 27 June 2009 12:21
The removal of the cuticle from a leaf would most likely result in an increase on the leaf's
Correct Answer: Option C – Water loss
The cuticle is the waxy covering on the surface of a leaf that prevents water from evaporating. It does not change the size, or surface area of the leaf. Food production might actually decrease without a cuticle since water is necessary for photosynthesis. The cuticle may also help to resist fungi, so by removing it you would be decreasing the fungus resistance.
Food production in plants occurs by photosynthesis. Photosynthesis is a process that converts carbon dioxide into organic compounds, especially sugars, using the energy from sunlight. Photosynthesis occurs in plants, algae, and many species of bacteria. With the exception of some bacteria, all use water and carbon dioxide as initial substrates and release oxygen as a waste product.
The ability to resist the formation of fungus growths is referred to as fungus resistance.
Living Environment Regents Review Practice Homeostasis Question 9
Saturday, 27 June 2009 12:22
In some individuals, the immune system attacks substances such as grass pollen that are usually harmless, resulting in
A)A form of cancer
Correct Answer: Option D - Allergic reaction
An allergic reaction is the body's way of responding to an "invader." When the body senses a foreign substance, called an antigen, the immune system is triggered. The immune system normally protects the body from harmful agents such as bacteria and toxins. Its overreaction to a harmless substance (an allergen) is called a hypersensitivity, or allergic, reaction.
Anything can be an allergen. Common dust, pollen, plants, medications, certain foods, insect venoms, viruses, or bacteria are examples of allergens.
Reactions may be in one spot, such as a small skin rash or itchy eyes, or all over, as in a whole body rash.
A reaction may include one or several symptoms
Cancer is a class of diseases in which a group of cells display uncontrolled growth (division beyond the normal limits), invasion (intrusion on and destruction of adjacent tissues), and sometimes metastasis (spread to other locations in the body via lymph or blood). These three malignant properties of cancers differentiate them from benign tumors, which are self-limited, and do not invade or metastasize.
Insulin is a hormone that has extensive effects on metabolism and other body functions, such as vascular compliance. Insulin causes cells in the liver, muscle, and fat tissue to take up glucose from the blood, storing it as glycogen in the liver and muscle, and stopping use of fat as an energy source.
Mutations are changes to the nucleotide sequence of the genetic material of an organism. Mutations can be caused by copying errors in the genetic material during cell division, by exposure to ultraviolet or ionizing radiation, chemical mutagens, or viruses, or can be induced by the organism itself, by cellular processes such as hypermutation.
Living Environment Regents Review Practice Homeostasis Question 10
Saturday, 27 June 2009 12:25
If a human system fails to function properly, what is the most likely result?
A)A stable rate of metabolism
B)A disturbance in homeostasis
C)Change in the method of cellular respiration
D)Change in the function of DNA
Correct Answer: Option B - A disturbance in homeostasis
Homeostasis is the property of a system, either open or closed, that regulates its internal environment and tends to maintain a stable, constant condition.
The internal equilibrium of the body, the ultimate gauge of its proper functioning, involves the maintenance of a constant rate of concentration in the blood of certain molecules and ions that are essential to life and the maintenance at specified levels of other physical parameters such as temperature. This is accomplished in spite of modifications of the environment.
Metabolism is the set of chemical reactions that occur in living organisms in order to maintain life. These processes allow organisms to grow and reproduce, maintain their structures, and respond to their environments. Metabolism is usually divided into two categories.Catabolism breaks down organic matter, for example to harvest energy in cellular respiration. Anabolism, on the other hand, uses energy to construct components of cells such as proteins and nucleic acids.
Cellular respiration is the set of the metabolic reactions and processes that take place in organisms' cells to convert biochemical energy from nutrients into adenosine triphosphate (ATP), and then release waste products. The reactions involved in respiration are catabolic reactions that involve the oxidation of one molecule and the reduction of another.
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