Important Questions for Class 11 Biology-Chemical Coordination and Integration

Hormones are chemicals providing chemical control and coordination of the body which assists in the regulation and integration of numerous activities of the human body. These are the hormones that govern the metabolism, development, and growth of our organs, a few cells, and the endocrine glands. The endocrine system consists of the hypothalamus, thyroid gland, pineal and pituitary gland, pancreas, thymus, parathyroid and the gonads (ovary and testis). Few other organs such as gastrointestinal tract, heart, kidney, etc also secrete hormones. Read on to discover more on how chemical integration and coordination is brought about in the human body

Very Short Answer Type Questions

Q.1. List the endocrine gland that is absent in males and the one absent in the female.
A.1. A pair of testes are present in the scrotal sac in males that performs functions of the endocrine gland as well as acts as a sex organ. This gland is absent in females as they possess a pair of ovaries situated in the abdomen. It produces progesterone and estrogen and is absent in males.
Q.2. Which amongst the two adrenocortical layers, zona reticularis, and zona glomerulosa lies outside wrapping the other?
A.2. The zona glomerulosa envelops the zona reticularis
Q.3. Define erythropoiesis. Name the hormone that triggers it.
A.3. The process of formation of RBC is known as erythropoietin. The peptide hormone erythropoietin produced from the juxtaglomerular cells of the kidney triggers the erythropoiesis.
Q.4. Which is the only hormone that is secreted by the pars intermedia of the pituitary gland?
A.4. Melanocyte Stimulating Hormone (MSH)
Q.5. Which is the endocrine gland that secretes calcitonin? What role does this hormone play?
A.5. It is produced by the parafollicular cells of the thyroid gland. It restricts excess Ca2+ and phosphate in the plasma by lowering mobilization from bones. Its deficiency causes osteoporosis or loss of bone density.
Q.6. Which hormone aids in cell-mediated immunity?
A.6. Thymosins play a significant role in the differentiation and development of T-lymphocytes that provide cell-mediated immunity.
Q.7. State if true or false
a) The gastrointestinal tract, heart, and kidney also produces hormones
b) Pars distalis produces six trophic hormones
A.7. a)The gastrointestinal tract, heart, and kidney also produces hormones – True b) Pars distalis produces six trophic hormones – True

Short Answer Type Questions

Q.1. State the significance of luteinizing hormones in males and females.
A.1. The luteinizing hormone in males triggers the production and secretion of hormones known as androgens from testes. Along with Follicle Stimulating Hormone (FSH), androgens control the spermatogenesis. The LH in females causes ovulation of the Graafian follicles and maintains the corpus luteum, developed from the traces of the Graafian follicles after ovulation that produces progesterone.
Q.2. Write about the importance of the second messenger in hormone action.
A.2. The hormones that do not enter the target cells, communicate with specific receptors situated on the surfaces of the target cell membranes and produces second messengers on the plasma membrane(inner side). In turn, the second messenger performs all the functions related to hormones.
Q.3. Which is the steroid that controls inflammatory responses? Name its source and its other functions.
A.3. Glucocorticoids. They are secreted by the adrenal cortex. They trigger gluconeogenesis, proteolysis, and lipolysis and hinder the cellular uptake and utilization of amino acids.
Q.4. Why do old people have a weak immunity system?
A.4. The thymus gland is situated on the dorsal side of the heart and the aorta and is a lobular structure. Derived from the embryo’s endoderm, the thymus produces the thymosin hormone that triggers the development of WBCs which produce immunity. In older individuals, the thymus degenerates thus causing a decreased thymosin secretion. Hence their immune system becomes weak.
Q.5. How does hypothyroidism affect the maturation and development of a growing baby, generally seen during pregnancy?
A.5. During pregnancy, hypothyroidism causes defective maturation and development of the fetus, that induces a stunted growth, low Intelligence Quotient(IQ), mental retardation, deaf-mutism, abnormal skin, etc.
Q.6. Differentiate between hyperthyroidism and hypothyroidism.
A.6. Hyperthyroidism is the over secretion of thyroid hormone and occurs due to the cancer of the thyroid gland whereas hypothyroidism is the low secretion of the thyroxine hormone.

Long Answer Type Questions

Q.1. A milkman’s cow refuses to give milk. On being fondled by the calf, the cow produced enough milk. Explain the significance of the endocrine gland and the pathway related to this response.
A.1. A neuroendocrine reflex is created when calf suckling occurs that causes an increase in the oxytocin from the neurohypophysis. In the hypothalamus, oxytocin is synthesized in specific nuclei, the paraventricular nucleus, and the supraoptic nucleus. Here the neurons produce the oxytocin precursor and bundle it into vesicles. The level of oxytocin in the blood gets concentrated within a minute or two after the stimulation which causes smooth muscle contraction of the udder causing milk to flow. An intra-udder hormone that functions like oxytocin would do a similar function. Following is a summarization. Suckling stimulus → Hypothalamus → Neurohypophysis → Oxytocin → Udder → Flow of milk
Q.2. A urine sample contained increased content of glucose and ketone bodies. Answer the questions below basis this observation.
a) Name the hormone and gland associated with this condition.
b) On which cells do these hormones act?
c) Name the condition. How can it be rectified?
A.2. a) Insulin hormone and Insulin gland. b) It acts on the β-cells of islets of Langerhans present in the pancreas c) Prolonged hyperglycemia causes diabetes mellitus that is linked to loss of glucose via urine and accumulation of harmful compounds called as ketone bodies. Insulin therapy can be successfully used to treat Diabetic patients.
Q.3. Describe the importance of hormones and endocrine glands responsible for regulating the Calcium Homeostasis.
A.3. The hormones and endocrine glands that regulate calcium homeostasis are thyroid and parathyroid glands and their related hormones which are Parathyroid hormone (PTH) and calcitonin. The endoderm of the embryo develops the parathyroid glands and has two types of cells – oxyphil cells and chief cells. The chief cells secrete the parathyroid hormone(PTH) which is involved in controlling phosphate and calcium stability between other tissues and blood. From bones, it causes the secretion of calcium into the blood. PTH causes an increase in the reabsorption of calcium by the organs of the body such as kidneys and intestine. The thyroid gland is the largest endocrine gland that is situated prefrontal to the thyroid cartilage of the larynx in the neck. It regulates the calcium homeostasis and releases thyrocalcitonin hormone which is produced by the ‘C’ cells. The hormone is secreted when the calcium concentration in blood is high. They lower the calcium level by suppressing the release of calcium ions from the bones. Hence calcitonin has a contrary effect on calcium in comparison to the parathyroid hormone.
Q.4. Explain why hypothalamus is a super master endocrine gland.
A.4. The hypothalamus controls an array of functions. It has many groups of neurosecretory cells known as nuclei that produce hormones. These hormones maintain the secretion and synthesis of pituitary hormones. The hormones produced by the hypothalamus are – the releasing hormones and the inhibiting hormones. The releasing hormones trigger the secretion of pituitary hormones and the inhibiting hormones hinder the secretions of the pituitary hormones. Through a portal circulatory system, the hormones arrive at the pituitary gland and check the functions of the anterior pituitary. Hypothalamus directly regulates the posterior pituitary. It also synthesizes two hormones – vasopressin and oxytocin which are further conveyed to the posterior pituitary. Learn more about chemical coordination and integration and other interesting aspects of biology by registering at BYJU’S.

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Practise This Question

Match the joints with their examples of where they are present in our body

i.Synovial jointa.Elbow jointii. Pivot jointb. Thumb jointiii. Saddle jointc. Carpal bone in wristiv. Hinge jointd. Hip jointv. Ball and socket jointe. Knee jointvi. Condyloid jointf. Neck (axis and atlas)