NCERT Exemplar Solutions for Class 10 Science Chapter 6 Life Processes (MCQ, SAQ and LAQ)
Chapter Name | NCERT Exemplar Solutions for Class 10 Science Ch 6 Life Processes |
Topics Covered |
|
Related Study |
|
Objective Type Questions for Life Processes
1. Which of the following statements about the autotrophs is incorrect?
(a) They synthesise carbohydrates from carbon dioxide and water in the presence of sunlight and
chlorophyll
(b) They store carbohydrates in the form of starch
(c) They convert carbon dioxide and water into carbohydrates in the absence of sunlight
(d) They constitute the first trophic level in food chains
Solution
(c) They convert carbon dioxide and water into carbohydrates in the absence of sunlight.
They need sunlight to convert carbon dioxide and water into carbohydrates.
2. In which of the following groups of organisms, food material is broken down outside the body and
absorbed?
(a) Mushroom, green plants, Amoeba
(b) Yeast, mushroom, bread mould
(c) Paramecium, Amoeba, Cuscuta
(d) Cuscuta, lice, tapeworm
Solution
(b) Yeast, mushroom, bread mould
Yeast, mushroom and bread mould are saprophytes and Saprophytes break the food material outside their body and absorbed.
3. Select the correct statement
(a) Heterotrophs do not synthesise their own food
(b) Heterotrophs utilise solar energy for photosynthesis
(c) Heterotrophs synthesise their own food
(d) Heterotrophs are capable of converting carbon dioxide and water into carbohydrates
Solution
(a) Heterotrophs do not synthesise their own food.
Heterotrophs either dependent on Phototrophs or other organisms for their food.
4. Which is the correct sequence of parts in human alimentary canal?
(a) Mouth → stomach → small intestine → oesophagus → large intestine
(b) Mouth →oesophagus → stomach → large intestine → small intestine
(c) Mouth → stomach → oesophagus → small intestine → large intestine
(d) Mouth → oesophagus → stomach → small intestine → large intestine
Solution
(d) Mouth → oesophagus → stomach → small intestine → large intestine
5. If salivary amylase is lacking in the saliva, which of the following events in the mouth cavity will be affected ?
(a) Proteins breaking down into amino acids
(b) Starch breaking down into sugars
(c) Fats breaking down into fatty acids and glycerol
(d) Absorption of vitamins
Solution
(b) Starch breaking down into sugars
Salivary Amylase enzyme present in the saliva breaks down starch into simpler sugar and helps in digesting them. Hence the breakdown of starch will be effected if salivary amylase is lacking in the saliva.
6. The inner lining of stomach is protected by one of the following from hydrochloric acid. Choose the correct one
(a) Pepsin
(b) Mucus
(c) Salivary amylase
(d) Bile
Solution
(b) Mucus
7. Which part of alimentary canal receives bile from the liver ?
(a) Stomach
(b) Small intestine
(c) Large intestine
(d) Oesophagus
Solution
(b) Small intestine
Bile goes to small intestine from gall bladder through hepta pancreatic duct.
8. A few drops of iodine solution were added to rice water. The solution turned blue-black in colour. This
indicates that rice water contains
(a) complex proteins
(b) simple proteins
(c) fats
(d) starch
Solution
(d) starch
Starch is made up of two components Amylose and Amylo pectin. When we add iodine to starch containing water Amylose reacts with iodine to form a blue colour complex. Here solution gives blue-black colour on adding Iodine which confirms the presence of starch in the rice water.
9. In which part of the alimentary canal food is finally digested?
(a) Stomach
(b) Mouth cavity
(c) Large intestine
(d) Small intestine
Solution
(d) Small intestine
Although primary digestion process is conducted in mouth and stomach most of the digestion process occur in small intestine and in large intestine digestion process will not take place.
10. Choose the function of the pancreatic juice from the following
(a) trypsin digests proteins and lipase carbohydrates
(b) trypsin digests emulsified fats and lipase proteins
(c) trypsin and lipase digest fats
(d) trypsin digests proteins and lipase emulsified fats
Solution
(d) trypsin digests proteins and lipase emulsified fats
Trypsin breaks down proteins into polypeptides and Lipase digest emulsified fat molecules into fatty acids and glycerol.
11. When air is blown from mouth into a test-tube containing lime water, the lime water turned milky due
to the presence of
(a) oxygen
(b) carbon dioxide
(c) nitrogen
(d) water vapour
Solution
(b) carbon dioxide
Caron dioxide reacts with lime water to convert it to milky.
12. The correct sequence of anaerobic reactions in yeast is
Solution
(d) (ii) and (iv)
(a) Nostrils → larynx → pharynx → trachea → lungs
(b) Nasal passage → trachea → pharynx → larynx → alveoli
(c) larynx → nostrils → pharynx → lungs
(d) Nostrils → pharynx → larynx → trachea → alveoli
(d) Nostrils → pharynx → larynx → trachea → alveoli
(a) trachea and larynx
(b) alveoli of lungs
(c) alveoli and throat
(d) throat and larynx
(b) alveoli of lungs
(i) Left atrium receives oxygenated blood from different parts of body while right atrium receives deoxygenated blood from lungs
(ii) Left ventricle pumps oxygenated blood to different body parts while right ventricle pumps deoxygenated blood to lungs
(iii) Left atrium transfers oxygenated blood to right ventricle which sends it to different body parts (iv) Right atrium receives deoxygenated blood from different parts of the body while left ventricle pumps oxygenated blood to different parts of the body
(a) (i)
(b) (ii)
(c) (ii) and (iv)
(d) (i) and (iii)
(c) (ii) and (iv)
(a) Valves in heart
(b) Thick muscular walls of ventricles
(c) Thin walls of atria
(d) All of the above
(a) Valves in heart
(a) Labeo, Chameleon, Salamander
(b) Hippocampus, Exocoetus, Anabas
(c) Hyla, Rana, Draco
(d) Whale, Dolphin, Turtle
(b) Hippocampus, Exocoetus, Anabas
(a) Pisces and amphibians
(b) Amphibians and reptiles
(c) Amphibians only
(d) Pisces only
(d) Pisces only
(a) They have thick elastic walls, blood flows under high pressure; collect blood from different organs and bring it back to the heart
(b) They have thin walls with valves inside, blood flows under low pressure and carry blood away from the heart to various organs of the body
(c) They have thick elastic walls, blood flows under low pressure; carry blood from the heart to various organs of the body
(d) They have thick elastic walls without valves inside, blood flows under high pressure and carry blood away from the heart to different parts of the body.
(d) They have thick elastic walls without valves inside, blood flows under high pressure and carry blood away from the heart to different parts of the body.
(b) urethra
(c) neurons
(d) nephrons
(a) water
(b) chlorophyll
(d) glucose
(a) water
(a) carbon dioxide
(b) water
(c) heamoglobin
(d) oxygen
(a) carbon dioxide
(a) Organisms grow with time
(b) Organisms must repair and maintain their structure
(c) Movement of molecules does not take place among cells
(d) Energy is essential for life processes
(c) Movement of molecules does not take place among cells
(a) glycogen
(b) protein
(c) starch
(d) fatty acid
(c) starch
(a) 6CO2 + 12H2O → C6H12O6 + 6O2 + 6H2O
(b) 6CO2 + H2O + Sunlight → C6H12O6 + O2 + 6H2O
(c) 6CO2 + 12H2O + Chlorophyll + Sunlight → C6H12O6 + 6O2 + 6H2O
(d) 6CO2 + 12H2O + Chlorophyll + Sunlight → C6H12O6 + 6CO2 + 6H2O
Solution
(c) 6CO2 + 12H2O + Chlorophyll + Sunlight→ C6H12O6 + 6O2 + 6H2O
Option (a) does not show the factors responsible for photosynthesis.
Option (b) is not a balanced equation.
Option (d) is wrong as it has CO2 in the products.
28. Choose the event that does not occur in photosynthesis
(a) Absorption of light energy by chlorophyll
(b) Reduction of carbon dioxide to carbohydrates
(c) Oxidation of carbon to carbon dioxide
(d) Conversion of light energy to chemical energy
Solution
(c) Oxidation of carbon to carbon dioxide
29. The opening and closing of the stomatal pore depends upon
(a) oxygen
(b) temperature
(c) water in guard cells
(d) concentration of CO2 in stomata
Solution
(c) water in guard cells
Opening of guard cells is facilitated by the entry of water inside guard cells. This make the guard cell become turgid. Closing of guard cells is facilitated by water coming out of guard cells. This will make the guard cells flaccid.
30. Choose the forms in which most plants absorb nitrogen
(i) Proteins
(ii) Nitrates and Nitrites
(iii) Urea
(iv) Atmospheric nitrogen
(a) (i) and (ii)
(b) (ii) and (iii)
(c) (iii) and (iv)
(d) (i) and (iv)
Solution
(b) (ii) and (iii)
Plants cannot absorb atmospheric Nitrogen. They can absorb the Nitrogen in the form of Nitrate, Nitrites and Urea present in the soil.
31. Which is the first enzyme to mix with food in the digestive tract?
(a) Pepsin
(b) Cellulose
(c) Amylase
(d) Trypsin
Solution
(c) Amylase
Amylase is secreted in mouth and acts on the starch to convert into simpler molecules. Hence Amylase is the first enzyme to mix with food in the digestive tract.
32. Which of the following statement(s) is (are) correct?
(i) Pyruvate can be converted into ethanol and carbon dioxide by yeast
(ii) Fermentation takes place in aerobic bacteria
(iii) Fermentation takes place in mitochondria
(iv) Fermentation is a form of anaerobic respiration.
(a) (i) and (iii)
(b) (ii) and (iv)
(c) (i) and (iv)
(d) (ii) and (iii)
Solution
(c) (i) and (iv)
Fermentation is carried out by anaerobes in the cytoplasm. Hence option (ii) and (iii) are wrong.
33. Lack of oxygen in muscles often leads to cramps among cricketers. This results due to
(a) conversion of pyruvate to ethanol
(b) conversion of pyruvate to glucose
(c) non conversion of glucose to pyruvate
(d) conversion of pyruvate to lactic acid
Solution
(d) conversion of pyruvate to lactic acid
Breakdown of Pyruvate in presence of oxygen takes place in mitochondria leading to the formation of Lactic acid. Due to workout oxygen is used for the production of energy leading to the lack of oxygen and production of lactic acid.
34. Choose the correct path of urine in our body
(a) kidney → ureter → urethra → urinary bladder
(b) kidney → urinary bladder → urethra → ureter
(c) kidney → ureters → urinary bladder → urethra
(d) urinary bladder → kidney → ureter → urethra
Solution
(c) kidney → ureters → urinary bladder → urethra
Urine from nephron is brought to the collecting duct of kidneys where the urine enters the ureters. There are 2 ureters, each opening from one kidney into the urinary bladder. The urinary bladder stores urine and it size increases as the amount of urine collected increases. When the CNS gives a voluntary message the muscles of bladder contract and the bladder sphincter relaxes thus excreting urine out through the urethra.
35. During deficiency of oxygen in tissues of human beings, pyruvic acid is converted into lactic acid in the
(a) cytoplasm
(b) chloroplast
(c) mitochondria
(d) golgi body
Solution
(a) cytoplasm
When there is lack of oxygen Breakdown of Pyruvate takes place in cytoplasm of muscle cells leading to the formation of Lactic acid.
Short Answer Questions for Life Processes
36. Name the following
(a) The process in plants that links light energy with chemical energy
(b) Organisms that can prepare their own food
(c) The cell organelle where photosynthesis occurs
(d) Cells that surround a stomatal pore
(e) Organisms that cannot prepare their own food
(f) An enzyme secreted from gastric glands in stomach that acts on proteins.
Solution
(a) Photosynthesis
(b) Autotrophs
(c) Chloroplasts
(d) Guard cells
(e) Heterotrophs
(f) Pepsin
37. “All plants give out oxygen during day and carbon dioxide during night”. Do you agree with this statement? Give reason.
Solution
The statement is wrong because plants respire every time and expel out Carbon - di - oxide every time but they give out oxygen only in the day time as photosynthesis process can take place only in the presence of sunlight.
38. How do the guard cells regulate opening and closing of stomatal pores?
Solution
Opening of guard cells is facilitated by the entry of water inside guard cells. This make the guard cell become
turgid. Closing of guard cells is facilitated by water coming out of guard cells. This will make the guard cells
flaccid.
Entry of water inside guard cells will make the cell turgid leading to the opening of stomata. Similarly cell become flaccid when water come out of guard cells, this leads to closing of the stomata.
39. Two green plants are kept separately in oxygen free containers, one in the dark and the other in continuous light. Which one will live longer? Give reasons.
Solution
Plant kept in continuous light live longer because plats release CO2 during respiration. In case of plant kept in
dark CO2 resulting in lack of oxygen and the plant will die earlier.
40. If a plant is releasing carbon dioxide and taking in oxygen during the day, does it mean that there is no photosynthesis occurring? Justify your answer.
Solution
If a plant is releasing carbon dioxide and taking in oxygen during the day means plant is respiring; it does not mean that there is no photosynthesis occurring in the plant. This is because Photosynthesis and respiration are two independent processes.
41. Why do fishes die when taken out of water?
Solution
Fishes can respire only by using dissolved oxygen. When we take fish out of water it cannot respire due to lack of dissolved oxygen and they die.
42. Differentiate between an autotroph and a heterotroph
Solution
|
Autotrophs |
Heterotrophs |
|
They can make their own food |
They cannot make their own food |
|
Ex : Plants and certain bacteria |
Ex : Animals, Fungi and protozoans |
Nutrition is an absolute necessity for the organisms because nutrition provides energy for carrying out metabolic activities.
Green plants are the sources of energy for all the heterotrophs on earth. Plants convert solar and chemical energy into viable food sources. If plants gets disappeared from the earth it lead to imbalance in the ecosystem and heterotrophs may die without food.
Coating Vaseline to the leaves of a healthy plants will clog its stomata pores and stops the respiration of plants and the plants dies.
|
Aerobic Respiration |
Anaerobic respiration |
|
Takes place in the presence of Oxygen |
Takes place in the absence of Oxygen |
|
Carbon – di – oxide and water are the end products |
Carbon - di – oxide and Lactic acid/ethanol are the end |
|
More efficient in energy production |
Less efficient in energy production |
|
Takes Place in animals and plants |
Takes place in unicellular organisms |
|
Column A |
Column B |
|
Phloem |
(i) Excretion |
|
Nephron |
(ii) Translocation of food |
|
Veins |
(iii) Clotting of blood |
|
Platelets |
(iv) Deoxygenated blood |
Column A | Column B |
Phloem | (ii) Translocation of food |
Nephron | (i) Excretion |
Veins | (iv) Deoxygenated blood |
Platelets | (iii) Clotting of blood |
- Artery has thick walls whereas Veins has thin walls.
- Arteries carries blood away from the heart but veins carry blood to the heart.
- In arteries valves are absent and in veins they are present
- In arteries blood flows under pressure but in veins there will be no pressure.
Adaptation of leaf for photosynthesis are as follows
- Surface of leaf is flat to allow greater exposure of light.
- Presence of chlorophyll to trap sunlight
- Presence of stomata on the lower surface for easy transpiration
Food of herbivores contains mostly cellulose. To digest cellulose herbivores need help of certain bacteria. In order to accommodate the microbes and to facilitate digestion of food herbivores has longer small intestine than carnivores.
Mucus prevent inner lining of stomach from HCL. Mucus prevents drying of inner lining of the stomach. Mucus helps in easy movement of food particles through digestive system. If mucus is not secreted food will not easily moved through digestive system. HCL will damage the stomach lining and the digestion process will not take place.
- Emulsification is a process of breakage of larger fats molecules into digestible fat globules.
- Emulsification aids action enzymes on fats by breaking larger fat molecules.
Peristalsis is the process that cause movement of food inside the alimentary canal.
Small intestine has specialized structures that facilitate absorption of digested food. Small intestine has number of folds that increase the area of absorption. Small intestine also has fingerlike projection called microvilli which are richly supplied by blood vessels.
|
Group A |
Group B |
|
(a) Autotrophic nutrition |
(i) Leech |
|
(b) Heterotrophic nutrition |
(ii) Paramecium |
|
(c) Parasitic nutrition |
(iii) Deer |
|
(d) Digestion in food vacuoles |
(iv) Green plant |
Group A | Group B |
(a) Autotrophic nutrition | (iv) Green plant |
(b) Heterotrophic nutrition | (iii) Deer |
(c) Parasitic nutrition | (i) Leech |
(d) Digestion in food vacuoles | (ii) Paramecium |
Rate of breathing in aquatic organisms much faster than in terrestrial organisms because availability of oxygen is less in water than on land, hence in order to obtain required oxygen aquatic organisms has to work hard.
In Humans blood flow in two direction simultaneously in one cardiac cycle. Oxygenated blood comes to heart from lungs and at the same time de-oxygenated blood goes from Heart towards lungs. Because of this double movement is blood circulation in human heart called double circulation.
Four chambered heart has the following advantages
- Clear cut division of labors among different chambers
- Segregation of oxygenated and deoxygenated blood in the heart.
- Efficiency of the heart will increase.
Major events of photosynthesis are
- Absorption of light energy by chlorophyll
- Conversion of light energy into chemical energy
- Splitting of water molecules into Hydrogen and Oxygen
- Reduction of CO2 to from carbohydrates.
(a) Cloudy days
(b) No rainfall in the area
(c) Good manuring in the area
(d) Stomata get blocked due to dust
(a) Rate of photosynthesis will reduce due to availability of sunlight.
Adenosine tri Phosphate (ATP) is the energy currency in the living organisms. It is produced in Mitochondria during respiration.
These all are parasite. They live on or inside another body to obtain food from the host. In obtaining food parasites always harm their host.
Role of mouth in digestion of food.
- Ingestion of food
- Breakage of food by Mastication
- Saliva aids easy swallowing of food
- Salivary amylase breaks starch into simpler carbohydrates.
Hydrochloric acid, pepsin and mucus are secreted by gastric gland present in the stomach. They have following functions.
- HCL Kills germs present in the food and it decreases PH of the stomach which is essential for the working of digestive enzymes.
- Pepsin digests protein.
- Mucus protects stomach’s inner line from HCL.
|
Column (A) |
Column (B) |
|
(a) Trypsin |
(i) Pancreas |
|
(b) Amylase |
(ii) Liver |
|
(c) Bile |
(iii) Gastric glands |
|
(d) Pepsin |
(iv) Saliva |
Column (A) | Column (B) |
(a) Trypsin | (i) Pancreas |
(b) Amylase | (iv) Saliva |
(c) Bile | (ii) Liver |
(d) Pepsin | (iii) Gastric glands |
(a) Trypsin
(b) Amylase
(c) Pepsin
(d) Lipase
Blood flow through veins does not exert pressure on walls of veins hence they have thin walls. Blood flow in arteries exerts high pressure on arterial walls hence they need thick walls.
Platelets are responsible for the clotting of the blood. If platelets are absent bllod will not clot. In case of injuries blood flow cannot be stopped without clotting and this may prove fatal for the person.
Most of the transport in plants occur through passive transport which does not require energy and plants stand still at one place and they will not travel in search of food Hence Plants require low energy compared to animals.
Water should enter the root xylem continuously to assist the various process such as photosynthesis. Continuous flow of water into root xylem is due to transpiration pull.
Transpiration is important for plants because of the following reasons.
- It creates transpiration pull to facilitate ascent of sap.
- Ascent of sap is necessary to make water available for photosynthesis.
- It helps a plant to get rid of excess water.
Leaves plays an important role in excretion in plants because CO2 is expelled out through pores of stomata present in the leaf. Plants shed leaves to get rid of excretory products deposited on them.
Long Answer Questions for Life Processes
Amoeba shows holozoic nutrition which is comprised of Ingestion, Digestion, Absorption, Assimilation and Egestion.
- Ingestion: Amoeba traps food particles through fingerlike projections called as pseudopodia. Pseudopodia present outside its body and helps in taking food along with water
- Digestion: Food vacuoles are made after ingesting the food. Enzymes are released in the food vacuole for digestion.
- Absorption: After digestion, nutrients enter the cytoplasm through osmosis.
- Assimilation: Nutrients are utilized by the cell for various purposes.
- Egestion: Food vacuole goes near the cell membrane to empty its contents outside the cell. This results in expulsion of waste materials from the cell.
- Buccal Cavity : Generally called as mouth and it consists of tongue, teeth and salivary gland. It is the entry site for the food to digestive system. Food is breakdown into simpler molecules by mastication in buccal cavity and salivary amylase breaks Starch into simpler carbohydrates in the Buccal cavity.
- Oesophagus : Buccaql cavity is connected to long tube like structure called as Oesophagus. Oesophagus connects the buccal cavity to stomach and assists in flow of food towards stomach. Oesophagus has a valve to prevent backflow of food particles.
- Stomach : Stomach is a J Shaped organ which has gastric glands in it. Gastric glands secrets Hydrochloric acid, Pepsin and Mucus that helps in the digestion of food.
- Small Intestine : Small intestine is highly coiled long structure. Small intestine performs major of the food absorption. Small intestine has specialized structures that facilitate absorption of digested food. Small intestine has number of folds that increase the area of absorption. Small intestine also has fingerlike projection called microvilli which are richly supplied by blood vessels.
- Large Intestine : This is shorter than small intestine and its lumen is larger than that of Small intestine. The major function of the large intestine is to absorb water from the remaining indigestible food matter and transmit the useless waste material from the body.
- Rectum : Large Intestine open into rectum. Waste materials and undigested food are stored in rectum.
- Anus : It is the opening at the end of alimentary canal. Solid waste materials leave the body through Anus.
Breathing in Humans has two processes 1) Inhalation 2) Exhalation
- Inhalation: Inhalation is the process of taking oxygen. During this process, ribs come out and diaphragm moves down. This increases the volume of the lungs and decreases the pressure. This will make the air move towards the lungs.
- Exhalation: Exhalation is a process of throwing out carbon-dioxide. During this process, ribs go down and diaphragm moves up. This decreases the volume of the lungs and increases the pressure. As a result air moves out of the lungs.
Soil is very important for the growth of the plant for the following reasons.
- Soil provides the base for the growth of the plants and provides a platform for the penetration of roots.
- It acts as a reservoir of the water.
- Soil has different minerals essential for the growth of the plant. Soil is the only medium from which soil obtain nutrients.
- Soil has organic materials essential for the growth of the plants.
- Soil has microorganisms that has symbiotic relationship with the plant and these microbes assist plant in their growth and life processes.
- Carbohydrate Digestion : Digestion of cabohydrates starts with buccal cavity where salivary enzymes breaks down the starch into simple sugar molecules. Other sugar molecules are breakdown to glucose in small intestine.
- Protein digestion : Proteins are partially digested by pepsin secreted by gastric glands present in the stomach. Then Pancreatic juice secrets trypsin and chymotrypsin enzymes in small intestine where complete digestion of proteins takes place.
- Fat Digestion : Fats are digested in small intestine. Bile juice present in the liver emulsifies the fat which breaks fats into small globules. These small fat globules are converted into glycerol and fatty acids by Lipase enzyme.
Photosynthesis is a process by which plants produce their own food by utilizing sunlight, CO2 and water. CO2 and water are converted to carbohydrates with the evolution of oxygen. Photosynthesis reaction can be given by following reaction.
Process of Photosynthesis is divided into 4 processes
- 1Absorption of light energy by chlorophyll
- Conversion of light energy into chemical energy
- Splitting of water molecules into Hydrogen and Oxygen
- Reduction of CO2 to produce carbohydrates
80. Explain the three pathways of breakdown in living organisms.
Solution
Glucose is first broken down to 3 carbon molecule called as pyruvate. This process takes place in the cytoplasm of all organisms. Pyruvate is further broken down by the flowing steps.
In yeast :
Pyruvate is broken down in the absence of oxygen and the process is called as anaerobic respiration. In yeasts pyruvate is broken down to produce CO2 and ethanol.
In Muscle Cells :
During rigorous physical activity energy demand of our muscles cells increases rapidly. This is compensated by anaerobic respiration in muscle cells. In muscle cells pyruvate is broken down into lactic acid.
In Mitochondria :
In case of aerobic respiration (in presence of oxygen) pyruvate is broken down in mitochondria. Here Pyruvate is broken down to produce H2O and CO2 . Aerobic respiration is most common in most of the organisms.
- Deoxygenated blood from different organs comes to the right atrium through the vena cava.
- From the right atrium, blood goes to the right ventricle. The tricuspid valve between the right atrium and right ventricle prevents the backflow of blood.
- From the right ventricle, blood goes to the lungs through pulmonary artery. Inside the lungs, carbon dioxide is removed from the blood and oxygen enters the blood.
- From the lungs, blood goes to the left atrium through pulmonary vein.
- From the left atrium, blood goes to the left ventricle.
- From the left ventricle, blood is pumped into the aorta so that it can be supplied to different organs.
Some substances in the initial filtrate, such as glucose, amino acids, salts and a major amount of water, are selectively re-absorbed as the urine flows along the tube. The amount of water re-absorbed depends on how much excess water is there in the body, and on how much of dissolved waste there is to be excreted. The urine forming in each kidney eventually enters a long tube, the ureter, which connects the kidneys with the urinary bladder.
Urine is stored in the urinary bladder until the pressure of the expanded bladder leads to the urge to pass it out through the urethra. The bladder is muscular, so it is under nervous control.