\n4. Kidneys<\/td>\n | (d) Undigested food<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n Answer: \n1 – b, 2 – c, 3 – d, 4 – a<\/p>\n V. Differentiate the following :<\/span><\/p>\na. Excretion and Secretion \nb. Absorption and Assimilation \nc. Ingestion and Egestion \nd. Diphyodont and Heterodont \ne. Incisors and Canines \nAnswer: \n(a) Excretion \nThe process of removal of nitrogenous wastes generated in the body is called excretion.<\/p>\n <\/p>\n
Secretion \nA process by which substances are produced and discharged from a cell, gland or organ for a function in the organism or for excretion.<\/p>\n (b) \nAbsorption \nAbsorption is the process by which nutrients obtained after digestion are absorbed by villi and circulated<\/p>\n \n- throughout the body by blood and lymph and supplied to all body cells according to their requirements.<\/li>\n
- It takes place in the small intestine. It<\/li>\n<\/ol>\n
Assimilation :<\/p>\n \n- Assimilation means the incorporation of the absorbed food materials into the tissue cells as their internal and hoihogenous component.<\/li>\n
- \u00a0takes place in the cells of the body.<\/li>\n<\/ol>\n
(c) Ingestion \nThe process of nutrition begins with intake of food, called ingestion.<\/p>\n Egestion : \nThe undigested or unassimilated portion of the ingested food material is thrown out from the body through the anal aperture as faecal matter. This is known as egestion or defaecation.<\/p>\n (d) Diphyodont \nIn human beings two sets of teeth (Diphyodont) are developed in their life time. The first appearing set of 20 teeth ca! led temporary or milk teeth are replaced by the second set of thirty two permanent teeth, sixteen in each jaw. This is called Diphyodont dentition.<\/p>\n Heterodont \nPermanent teeth are of four types according to their struture and function namely Incisors, Canines, Premolars and molars. This is called Heterodont dentition.<\/p>\n <\/p>\n
(e) Incisors\u00a0 :<\/p>\n \n- Used for cutting and biting.<\/li>\n
- In a human adult there are 8 incisors<\/li>\n<\/ol>\n
Canines<\/p>\n \n- Used for tearing and piercing.<\/li>\n
- In a human adult there are 4 canines.<\/li>\n<\/ol>\n
VI. Answer briefly :<\/span><\/p>\nQuestion 1. \nHow is the small intestine designed to absorb digested food? \nAnswer: \nSmall intestine comprises three parts- duodenum, jejunum and ileum. Ileum is the longest part of the small intestine. It contains minute finger-like projections called villi where absorption of food takes place. They are approximately 4 million in number. Internally, each villus contains fine blood capillaries and lacteal tubes.<\/p>\n Question 2. \nWhy do we sweat? \nAnswer: \nThe human body functions normally at a temperature of about 37\u00b0C. When it gets hot sweat glands start secreting sweat, which contains water with small amounts of other chemicals like ammonia, urea, lactic acid and salts (mainly sodium chloride). The sweat passes through the pores in the skin and gets evaporated, which reduces the body temperature.<\/p>\n <\/p>\n
Question 3. \nMention any two vital functions of the human kidney. \nAnswer: \nTwo vital functions of the kidneys are;<\/p>\n \n- Maintain the fluid and electrolyte balance in our body.<\/li>\n
- Maintain the osmotic pressure in blood and tissues.<\/li>\n<\/ol>\n
Question 4. \nWhat is micturition? \nAnswer: \nWhen the urinary bladder is full the urine is expelled out through the urethra. This process is called micturition. A healthy person excretes one to two litres of urine per day.<\/p>\n Question 5. \nName the types of teeth present in an adult human being. Mention the functions of each. \nAnswer: \nPermanent teeth are of four types (Heterodont), according to their structure and function namely incisors, canines, premolars, and molars.<\/p>\n Types of teeth and their functions : \n <\/p>\n <\/p>\n
Question 6. \nExplain the structure of nephron. \nAnswer: \n <\/p>\n \n- Each kidney consists of more than one million nephrons. Nephrons or uriniferous tubules are structural and functional units of the kidneys.<\/li>\n
- Each nephron consists of Renal corpuscle or Malphigian corpuscle and renal tubule.<\/li>\n
- The renal corpuscle consists of a cup-shaped structure called Bowman\u2019s capsule containing a bunch of capillaries called glomerulus.<\/li>\n
- Blood enters the glomerular capillaries through afferent arterioles and leaves out through efferent arterioles.<\/li>\n
- The Bowman\u2019s capsule continues as the renal tubule which consists of three regions proximal convoluted tubule, U-shaped hair pin loop, the loop of Henle and the distal convoluted tubule.<\/li>\n
- The distal convoluted tubule which opens into the collecting tubule. The nitrogenous wastes are drained into renal pelvis of kidney which leads to ureters and stored in the urinary bladder.<\/li>\n
- Urine is expelled out through the urethra.<\/li>\n<\/ul>\n
<\/p>\n
VII. Answer in detail :<\/span><\/p>\nQuestion 1. \nDescribe the alimentary canal of man. \nAnswer: \nAlimentary canal is a muscular coiled, tubular structure. It consists of mouth, buccal cavity, pharynx, oesophagus, stomach, small intestine (consisting of duodenum, jejunum and ileum), large intestine (consisting of caecum, colon and rectum) and anus. \n <\/p>\n Mouth: Leads into the buccal cavity. It is bound 2 soft movable upper and lower lips. The buccal cavity is a large space-bound above by the palate (which separates the windpipe and food tube), below by the throat and on the sides by the jaws. The jaws bear teeth.<\/p>\n Teeth: Hard structures meant \nfor holding, cutting, grinding and crushing the food. In human beings, two sets of teeth (Diphyodont) are developed in their lifetime.<\/p>\n Each tooth has a root fitted in the gum (Theocodont). Permanent teeth are of four types (Heterodont), according to their structure and function namely incisors, canines, premolars and molars.<\/p>\n Dental formula represents the number of different type of teeth present in each half of a jaw (upper and lower jaw). \nFor Permanent teeth in each half of upper and lower jaw: \n\\(\\frac{2,1,2,3}{2,1,2,3}\\) = 16 x 2 = 32<\/p>\n <\/p>\n
Salivary glands: There are 3 pairs<\/p>\n \n- Parotid glands Largest salivary glands, which lie in the cheeks in front of the ears.<\/li>\n
- Sublingual glands Smallest lands and lie beneath the tongue.<\/li>\n
- Submaxillary or Submandibular-glands-lie at the angles of the lower jaw.<\/li>\n<\/ul>\n
Tongue: Muscular, sensory organ – Helps in mixing the food with the saliva.<\/p>\n Pharynx: It is a membrane-lined cavity behind the nose and mouth, connecting them to the oesophagus. Serves as” a pathway for the movement of food from mouth to oesophagus.<\/p>\n Oesophagus: Muscular-membranous canal about 22 cm in length. It conducts food ‘ from pharynx to the stomach by peristalsis (wave-like movement) produced by the rhythmic contraction and relaxation of the muscular walls of alimentary canal.<\/p>\n Stomach: Wide J-shaped muscular organ located.<\/p>\n Location: Between oesophagus and the small intestine.<\/p>\n Small intestine: The small intestine is the longest part of the alimentary canal, which is a long coiled tube measuring about 5 – 7 m. It comprises three parts- duodenum, jejunum, and ileum.<\/p>\n \n- Duodenum – C-shaped and receives the bile duct (from the liver) and pancreatic duct (from Pancreas). \u2019<\/li>\n
- Jejunum Middle part of the small intestine. A short region of the small intestine.<\/li>\n
- Ileum – Forms the lower part of the small intestine and opens into the large intestine.<\/li>\n<\/ul>\n
Liver: Largest digestive gland of the body, reddish-brown in colour. Bile salts help in the digestion of fats by emulsification (conversion of large fat droplets into small ones).<\/p>\n Pancreas: Lobed, a leaf-shaped gland situated between the stomach and duodenum. \nPancreas acts both as an exocrine gland and as an endocrine gland.<\/p>\n Large intestine: The unabsorbed and undigested food is passed into the large intestine. \nIt extends from the ileum to the anus. About 1.5 meters in length. Has 3 parts colon and rectum.<\/p>\n Caecum: Small blind pouch-like structure at the junction of the small and large intestine. \nFrom its blind end, a finger-like structure called a vermiform appendix arises. It is a vestigeal (functionless) organ in human beings.<\/p>\n Colon: Much broader than ileum. Passes up the abdomen on the right ascending colon, \ncrosses to the left just below the stomach (transverse colon) and down on the left side – (descending colon).<\/p>\n Rectum: Last part which opens into the anus muscles called mi;)! Spain opens when passing stools.<\/p>\n <\/p>\n
Question 2. \nExplain the structure of the kidney and the steps involved in the formation of urine. \nAnswer: \nSTRUCTURE OF KIDNEYS:<\/p>\n \n- Kidneys are bean-shaped reddish-brown in colour.<\/li>\n
- The kidneys lie on either side of the vertebral column in the abdominal cavity attached to the dorsal body wall.<\/li>\n
- The right kidney is placed lower than the left kidney as the liver takes up much space on the right side.<\/li>\n
- Each kidney is about 11 cm long, 5 cm wide, and 3 cm thick.<\/li>\n
- Internally the kidney consists of:\n
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