Biology Solved Homework Solution Sample

QUESTION

Part I–True and False: For each of the following statements, write the word true next to the statement if it is true. If the statement is false, change the underlined word(s) to make the statement true. Write the correction in the line provided in front of the question. (2 points each)

1. __________________ Increases in intensity of a stimulus are transmitted by a larger action potential.

2. __________________ Steroid hormones pass through the cell membrane.

3. __________________ The occipital lobe of the cerebrum receives and evaluates input for smell and hearing.

4. ___________________ Filtering of sensory inputs to the cerebral cortex is done at the pons..

5. __________________ Reference a membrane potential, the exterior of the cell has a net negative charge and the interior is neutral.

6. ___________________ An antibody is a cell that seeks out any antigen and inactivates it.

7. ____________________ Helper T cells can stimulate the proliferation of cytotoxic T cells but not that of B cells.

8. ____________________ The secondary immune response to a previously encountered pathogen is swifter and stronger than the primary immune response.

9. ____________________ Releasing hormones are secreted by the pituitary gland and increase release of hormones at the target organ.

10. ___________________ Cytotoxic T cells produce cytotoxins which cause growth of infected cells.

Part II—Short Answer Questions

1. When a body is in a hypoxic (low oxygen levels) situation, the nervous system is the first system to be affected and the effects occur within minutes. From your knowledge of how neurons prepare to and actually transmit signals, explain why that is so. BE DETAILED ABOUT NEURON FUNCTION! (10 pts)

2. For each of the following sets of symptoms, tell me what part of the vertebrate brain is defective (more specific than hindbrain of forebrain). Justify your answer and be as detailed as possible. (3 pts each)

a. Coordination of muscular activities is being lost. Patient is not paralyzed but has great difficulty coordinating movements of different muscle groups–walking is noticeably affected.

b. Knows what she wants to say but is unable to speak the words.

c. Unable to match visual information with the names of the objects.

d. Heart rate, breathing rate, and blood pressure uncontrollable. Results in death

3. Use the following diagram for this question. It has two parts–A and B.

A. Label each of the arrows above (3 Pts each)

B. Describe the function (what they do) of each of the structures above and how they interact with each other. (10 pts) (More space on next page)

4. Fred shows symptoms of elevated thyroid hormone production. He shows elevated levels of TSH and very low levels of Thyroxin (T4). The doctor believes he has an autoimmune disorder and is producing antibodies that affect the receptors for TSH on the thyroid or the receptors for thyroxine in the pituitary gland.

a. Explain the consequences for both thyroxin and TSH if the auto-antibodies do each of the following: (EXPLAIN is more than telling me what the levels will be. Explain why) (3 pts each)

1. block the thyroxin receptors on the pituitary.

2. stimulate the thyroxin receptors on the pituitary

3. block the TSH receptors on the thyroid

4. stimulate the TSH receptors on the thyroid

b. Explain which of these is a likely explanation of Fred’s condition (5 pts)

5. Referring to either question #2 OR #4 above, tell me which of five core concepts (Do Not Use Systems Concept) is illustrated by that information and give some details as to how you arrived at that conclusion. (10 pts)

6. Explain how the overall organization of the immune system illustrates the Biology Systems Core Concept. Make sure you include how how the innate and adaptive immune systems are related and how the different types of lymphocytes interact with each other. You may find a diagram useful as part of your answer.

(15 pts)

7. Compare the nervous system and endocrine system in terms of how signals are transmitted, how each can activate specific cells and not others, and speed of response. GIVE SPECIFIC EXAMPLES AND EXPLAIN HOW THEY ILLUSTRATE YOUR POINT (21 pts)

8. Referring to question #7 above, explain one example from EACH system of how the Structure and Function Core Concept is illustrated. (What specific structure facilitates what specific function in each system.) (10 pts)

Answer only ONE of the questions below. If you answer more than one only the first will be graded

Describe one type of immune system malfunction (includes hypersensitivities). Include which parts of the immune system are defective and what is the result (symptoms).

A person has had an aneurism rupture in the brain (blood vessel breaks). In which part of the brain would this most quickly lead to death and why.

ANSWER

1. ___true_______ Increases in intensity of a stimulus are transmitted by a larger action potential.

2. ___true_____ Steroid hormones pass through the cell membrane.

3. _false (temporal lobe)__ The occipital lobe of the cerebrum receives and evaluates input for smell and hearing.

4. false (thalamus)___ Filtering of sensory inputs to the cerebral cortex is done at the pons..

5. __false (positive) and ( negative)_________ Reference a membrane potential, the exterior of the cell has a net negative charge and the interior is neutral.

6. __false (protein)___ An antibody is a cell that seeks out any antigen and inactivates it.

7. ____true_________ Helper T cells can stimulate the proliferation of cytotoxic T cells but not that of B cells.

8. __true__________ The secondary immune response to a previously encountered pathogen is swifter and stronger than the primary immune response.

9. _false (hypothalamus)__ Releasing hormones are secreted by the pituitary gland and increase release of hormones at the target organ.

10. _false (apoptosis)_______ Cytotoxic T cells produce cytotoxins which cause growth of infected cells.

Part II—Short Answer Questions

Ans.

Hypoxic brain injuries: Hypoxic brain injuries occur when the brain receives less oxygen than it needs, but is not completely deprived of oxygen. The brain represents just 2% of body weight, yet it uses about 20% of the body’s oxygen supply. Without it, the brain can’t perform even the most basic functions. The brain relies on glucose to power neurons that control everything from conscious functions like planning and thought to automatic unconscious processes like heart rate and digestion. Without oxygen, the brain’s cells cannot metabolize glucose, and therefore cannot convert glucose into energy. When your brain is deprived of oxygen, then, the ultimate cause of brain death is inadequate energy to power the brain’s cells.

How neurons prepare to and actually transmit signals: Examining the responses of hypoxia-tolerant neurons to decreased oxygen availability is of interest for several reasons. First, oxygen signaling is well developed in hypoxia-tolerant neurons, making them ideal models for studying signal transduction processes during adaptations to hypoxia. Second, hypoxia-tolerant neurons are useful models for distinguishing between injury and adaptation induced by hypoxia. This is of obvious interest in determining the relevance of proposed therapeutic interventions for patients with hypoxic or ischemic diseases. Third, these neurons may help in the identification of entirely new targets for treating diseases that involve hypoxia.

Coordination of muscular activities is being lost. Patient is not paralyzed but has great difficulty coordinating movements of different muscle groups–walking is noticeably affected.

Ans.: Cerebellum, the peripheral nerves of the body and the spinal cords involved the coordinated movements.

Diseases and injuries that damage or destroy any of these structures can lead to ataxia. Ataxia can affect coordination, speech, and balance. It can also make it hard to swallow and walk.

b. Knows what she wants to say but is unable to speak the words.

Ans: Expressive aphasia is a disorder that often occurs after a stroke injures the frontal regions of the left hemisphere. Individuals with expressive aphasia have difficulties in expressing, understanding, reading, or writing oral and written language.

c. Unable to match visual information with the names of the objects.

Ans: Visual agnosia is the inability to recognize things using a particular system, despite normal sensation. It occurs when the brain suffers damage along the pathways that connect the occipital lobe of the brain with the parietal and temporal lobes. The occipital lobe assembles incoming visual information. The parietal and temporal lobes allow you to understand the meaning of this information.

d. Heart rate, breathing rate, and blood pressure uncontrollable. Results in death

Ans.: Bodily processes that are controlled automatically like blood pressure, heart rate and respiratory rate. The medulla oblongata basically detects carbon dioxide and oxygen levels in the blood stream and determines what changes need to happen in the body. So, any damage caused to it can have serious.

3. Use the following diagram for this question. It has two parts–A and B.

A. Label each of the arrows above (3 Pts each)

Neurosecretory cells

2. Hypophyseal portal vein

3. Anterior pituitary lobe (adenohypophysis)

4. Hypothalamus

5. Posterior pituitary lobe (neurohypophysis)

B. Describe the function (what they do) of each of the structures above and how they interact with each other. (10 pts) (More space on next page)

The pituitary gland is attached to the bottom of the hypothalamus by the pituitary stalk called the infundibulum. The hypothalamus controls the glandular secretion of the pituitary gland and oversees many internal body conditions (homeostasis). It has endocrine and neural components so influences body through circulatory or nervous system.

The pituitary gland can be referred to as the master gland because it is the main site of hormone released from the brain. It is divided anatomically into two sections – an adenohypophysis (the anterior pituitary lobe) and a neurohypophysis (the posterior pituitary lobe).

Communication between the anterior pituitary and the hypothalamus occurs through the chemicals (releasing and inhibiting hormones) that are produced by the hypothalamus and delivered to the anterior pituitary by a means of a special portal blood system called the hypophyseal portal system. Neurosecretory cells (specialized neurons of the hypothalamus) produce releasing and inhibiting hormones. And the communication between the posterior pituitary and the hypothalamus occurs through neurosecretory cells. Hormones produced by the cell bodies of the neurosecretory cells are packaged in vesicles and transported through the axon and stored in the axon terminals to a capillary network within the posterior pituitary.

a. Explain the consequences for both thyroxin and TSH if the auto-antibodies do each of the following: (EXPLAIN is more than telling me what the levels will be. Explain why) (3 pts each)

1. block the thyroxin receptors on the pituitary.

Too little production of thyroxine by the thyroid gland is known as hypothyroidism

2. stimulate the thyroxin receptors on the pituitary

Ans. Too much production of thyroxine by the thyroid gland is known as hyperthyroidism

3. block the TSH receptors on the thyroid

Ans: if a person has too little thyroid stimulating hormone, it is most likely that their thyroid gland is making too much thyroid hormone, that is , they have an overactive thyroid or hyperthyroidism.

4. stimulate the TSH receptors on the thyroid

Ans: if a person has too much thyroid stimulating hormone, it is most likely that their thyroid gland is not making enough thyroid hormone, that is , they have an underactive thyroid or hypothyroidism.

b. Explain which of these is a likely explanation of Fred’s condition (5 pts)

Ans.: Graves’ disease is an immune system disorder that results in the overproduction of thyroid hormones or hyperthyroidism.

Ans:

Five core concept of nervous system:

The brain makes it possible to communicate knowledge through spoken and written language.
The brain makes sense of the world by using all available information, including senses, emotions, instincts, and remembered experiences.
Consciousness depends on normal activity of the brain.
Sensory circuits (sight, touch, hearing, smell and taste) bring information to the nervous system, whereas motor circuits send information to muscles and glands.
Some injuries harm nerve cells, but the brain often recovers from stress, damage or disease.

(15 pts)

Ans.:

Innate immunity is the first line of defence of body against invaders. The epithelial and mucosal linings of our respiratory and GI tracts, as well as our skin are major components of the innate immune system. These act as physical and chemical barriers against pathogens. Cells known as macrophages also play a large role in innate immunity. Macrophages recognize bacterial or viral components such as lipopolysaccharide (LPS) or double-stranded RNA (dsRNA), via special receptors known as Toll-like receptors (TLRs). TLR activation cause macrophages to secrete cytokines (small molecules involved in cell signaling and attraction), as well as to phagocytose the infected cells. The innate immune system is required to activate our adaptive immune system.

Figure 1. White blood cells play major roles in both the innate and adaptive immune responses.

The adaptive immune response is mediated by immune cells known as lymphocytes. This immunity develop after infection or vaccination. These are B and T cells. B cells secrete antibodies, highly specific protein molecules that bind to a specific pathogen. These antibodies bind specific parts of pathogens known as antigens – either presented extracellularly on infected cells or free-floating in the body. Antibody binding attracts mechanisms that will then attack and destroy the infected cell or pathogen. Some of these B cells become memory cells, which help the body “remember” the disease and prevent re-infection. T cells can either be helper T cells or cytotoxic T cells, and bind pathogens via the T-cell receptor (TCR), which senses specific protein sequences. Helper T cells activate B cells, attract macrophages, and secrete cytokines. Cytotoxic T cells create pores in infected cells through which they introduce chemicals that trigger apoptosis, thus actively killing the cell.

Ans.: all living cells have the ability to react to stimuli. Nervous tissue is specialized to react to stimuli and to conduct impulses to various organs in the body which bring about a response to the stimulus. Neurons communicate using both electrical and chemical signals. Electric currents in the vastly complex system of billions of nerves in our body allow us to sense the world, control parts of our body, and think. These are representative of the three major functions of nerves. First, nerves carry messages from our sensory organs and others to the central nervous system, consisting of the brain and spinal cord. Second, nerves carry messages from the central nervous system to muscles and other organs. Third, nerves transmit and process signals within the central nervous system. The sheer number of nerve cells and the incredibly greater number of connections between them makes this system the subtle wonder that it is. Nerve conduction is a general term for electrical signals carried by nerve cells. It is one aspect of bioelectricity, or electrical effects in and created by biological systems.

The endocrine system is a control system of ductless glands that secrete chemical messengers called hormones that circulate within the body via the blood stream to affect distant cells within specific organs. Endocrine glands secrete their product immediately into the blood or intestinal fluid, without storage of chemical. Hormones act as ‘messengers’ and are carried by the bloodstream to the different cells in the body, which interrupt these messages and act on them. This process takes significantly longer than that of the nervous system, as endocrine hormones must first be synthesized, transported to their target cell, and enter or signal the cell. However, although hormones act more slowly than a nervous impulse, their effects are typically longer lasting.

Ans.: 1. Neurons communicate using both electrical and chemical signals.

Sensory stimuli are converted into electrical signals.
Action potentials are electrical signals carried along neurons.
Electrical signal in muscle cause contraction and movement.

Endocrine physiology is concerned with the maintenance of various aspects of homeostasis. The mediators of such control mechanisms are soluble factors known as hormones.

Answer only ONE of the questions below. If you answer more than one only the first will be graded

Describe one type of immune system malfunction (includes hypersensitivities). Include which parts of the immune system are defective and what is the result (symptoms).

Ans- Improper functioning of immune system may cause discomfort (allergy), disease (AIDS) or even death (anaphylactic shock) hypersensitivity is an excessive immune response which leads to undesirable consequences, i.e., tissue or organ dysfunction or damage.

Hypersensitivity or allergy: when a person show hyper response or hypersensitiveness for a common agent or antigen then it is called hypersensitivity or allergy.

Physiology of allergy: more secretion of histamine from mast cells and more production IgE antibodies in response to a common antigen or allergen.

Manifestations:

Bronchial asthma: it is common manifestation of allergy. It is allergy of lungs when an allergen enters inside the body by inhalation. It comes in contact with respiratory tube. This is characterized by the spasm of the smooth muscles present in the walls of the bronchiole. It is generally caused by the hypersensitivity of the bronchiole to the foreign substance present in the air passing through it. The mucus membranes on the wall of the air passage start secreting excess amount of mucous, which may close the bronchi, as well as bronchiole.

Symptoms of the bronchial asthma: coughing and difficulty in breathing mainly during expiration (wheezing).

Prevention and cure:

Avoiding exposure to the foreign substance or allergens is the best preventive measure.
Hyposensation (by exposing small doses of the specific allergen) is the other preventive measure.
Antibiotic therapy for removing the infection, and use of bronchodilator drugs, as well as inhalers for symptomatic relief.

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