Life Processes Flashcards
(30 cards)
What are Life Processes?
The maintenance funcs of living organisms must go on even when they are not doing anything particular.
Even when we are just sitting in class or just asleep this maintenance job has to go on.
The processes which together perform this maintenance job are called life processes.
What has to be done to make external sources of energy beneficial?
The outside sources of energy could be quite varied, since the environment is not under the control of the individual organism.
These sources of energy, therefore, need to be broken down or built up in the body, and must be finally converted to a uniform source of energy that can be used for the various molecular movements needed for maintaining living structures, as well as for the kind of molecules the body needs to grow.
For this, a series of chemical reactions in the body are necessary. Oxidising-reducing reactions are some of the common means to break-down molecules.
For this, many organisms use oxygen sources from outside the body.
The process of acquiring oxygen from outside the body, and to use it in the process of beak-down of food sources for cellular needs, is what we call respiration.
Why will simple diffusion not meet the requirements of all the cells in multicellular organisms?
In the case of a single-celled organism, no specific organs for taking in food, exchange of gases or removal of wastes may be needed because the entire surface of the organism is in contact with the environment.
In multi-cellular organisms all the cells may not be be in direct contact with the surrounding environment.
Also for multi-cellular organisms, diffusion is a very slow process.
Thus simple diffusion will not meet the requirements of all the cells.
Define Excretion
When chemical reactions use carbon source and oxygen for energy generation, they create by-products that are not only useless but harmful for the cells.
These waste by-products are therefore needed to be removed from the body.
This process of eliminating metabolic waste from an organism is called excretion.
How do living things get their food?
Some organisms use simple food material obtained from inorganic sources in the form of carbon dioxide and water. Such organisms are called autotrophs. They include green plants and some bacteria.
Other organisms, like the heterotrophs, utilise complex substances. These complex substances have to be broken down into simpler ones before they can be used for the upkeep and growth of the body. Heterotrophic organisms include animals and fungi.
Heterotrophs use bio-catalysts called enzymes for break down of food. The heterotroph’s survival depends directly or indirectly on autotrophs.
What events occur during the process of photosynthesis?
(i) Absorption of light energy by chlorophyll
(ii) Conversion of light energy to chemical energy
(iii) Splitting of water molecules into hydrogen and oxygen.
(iv) Reduction of carbon dioxide to carbohydrates.
Explain digestion in human beings.
A fluid called saliva is excreted by salivary glands
Biological catalyst called enzymes break down the food for it to be absorbed by the alimentary canal.
The saliva contains an enzyme called salivary amylase that breaks down starch which is a complex molecule to give simple sugar.
The lining of the alimentary canal has muscles that contract rhythmically in order to push the food forward. These peristaltic movements occur all along the gut.
Then the food is taken to the stomach. The stomach is a large organ which expands when food enters it. The muscular walls of the stomach help in mixing the food thoroughly with more digestive juices. The stomach is taken care of by gastric glands present in the wall of the stomach. These release Hydrochloric Acid (HCl), for creating an acidic medium and also activating Pepsin. Pepsin is used to break large protein molecules to small protein molecules. And the mucus helps in protecting the inner lining of the stomach from the action of acid under normal conditions.
The food coming from the stomach is acidic and has to be alkaline for the pancreatic enzymes to act.
Bile juice is secreted from the liver to change the food’s medium to alkaline and also break down large fat globules into small fat globules using Bile salt (part of bile juice).
The pancreas secretes pancreatic juice which contain enzymes like trypsin for further breaking the small protein molecules to peptones and lipase for breaking down emulsified fats.
The walls of the small intestine contain glands which secrete intestinal juice. The enzymes present in it convert peptones to amino acids, complex carbohydrates into glucose and fats to fatty acids and glycerol.
Digested food is taken up by the walls of the small intestine. The inner lining of the small intestine has numerous finger-like projections called villi which increase surface area for absorption.
The unabsorbed food is sent into the large intestine where it’s wall absorbs more water from this material.
The rest of the material is removed from the body via anus. The exit of this waste material is regulated by the anal sphincter.
What is the function of plasma?
Plasma transports food, carbon dioxide and nitrogenous wastes in dissolved form.
How do different organisms provide themselves with energy?
Diverse organisms provide themselves with energy in different ways - some use oxygen to break-down glucose completely into CO2 and H2O, some use other pathways that do not involve oxygen.
In all cases, the first step is the break down of glucose, a six-carbon molecule, into a three-carbon molecule called pyruvate. This process takes place in cytoplasm.
Further, pyruvate may be converted into ethanol and CO2. This process takes place in yeast fermentation. Since this process takes place in absence of O2, it is called anaerobic respiration.
Break down of pyruvate takes place in mitochondria. This process breaks up the three-carbon pyruvate molecule to give three molecules of CO2. The other product is water. Since this process takes place in presence of oxygen, it is called Aerobic Respiration.
Sometimes, when there is a lack of O2 in our muscle cells, another pathway for the break-down of pyruvate is taken. Here pyruvate is converted into lactic acid which is also a three-carbon molecule.
What are the differences b/w Aerobic and Anaerobic respiration?
Aerobic Respiration -
Takes place in presence of O2.
End products are CO2 + Water + ATP.
Energy produced is much more than anaerobic respiration.
Completes reaction in the mitochondria.
Anaerobic Respiration -
Takes place in absence of O2.
End products are ethanol and CO2 or lactic acid and ATP.
Energy produced is less than Aerobic Respiration.
Occurs in the cytoplasm.
Why do aquatic organisms have a higher breathing rate than terrestrial organisms?
Since the amount of dissolved oxygen in water is fairly low compared to the amount of oxygen in the air, the rate of breathing in aquatic organisms is much faster than rate of breathing in terrestrial organisms.
What are the characteristics of lungs?
- thin, delicate and moist
- large surface area because of branching of bronchioles.
- rich supply of blood due to presence of capillaries.
Explain the process of Respiration.
You breathe air through your mouth and nose.
From there, the air moves into your Pharynx, which is a passageway in your throat that leads to both your stomach and lungs. The Epiglottis is a flap like structure that prevents food from entering your trachea and air entering your oesophagus.
From there, air moves into the Larynx, a part of the air passage where your vocal cords are located.
The air then moves into your trachea, which is lined with cartilage to keep it firm and ensure it doesn’t collapse. The trachea also has tiny hairlike structures called cilia and mucus to trap bacteria, dust, or any particles that shouldn’t be going into your lungs.
Next, the air moves into tubes leading to your lungs called Bronchi. They further lead to smaller tubes bronchioles.
Bronchioles connect directly to Alveoli, which are millions of tiny air sacs. Oxygen from the air in the alveoli moves into the blood in the capillaries to be circulated throughout your body so that respiration can happen in all your cells. At the same time, carbon dioxide waste in blood moves into air in the alveoli to be exhaled.
How does the heart work?
Oxygen-rich blood from the lungs comes out to the thin walled upper chamber on the left, the left atrium. The left atrium relaxes when it is collecting this blood. It then contracts, while the next chamber the left ventricle, relaxes, so that the blood is transferred to it. When the muscular left ventricle contracts in its turn, the blood is pumped out to the rest of the body.
De-oxygenated blood comes from the body to the upper chamber on the right, the right atrium, as it relaxes. As the right atrium contracts, the corresponding lower chamber, the right ventricle, dilates. This transfers blood to the right ventricle which in turn pumps it to the lungs for oxygenation.
Why do ventricles have thicker walls?
Since ventricles have to pump blood into various organs, they have thicker muscular walls than atria do.
What is the significance of valves?
Valves are present in the veins, atria and ventricles to ensure that blood doesn’t flow backwards.
Explain process of double circulation, why is it necessary?
The human heart is divided into four chambers − the right atrium, the right ventricle, the left atrium, and the left ventricle.
Flow of blood in the heart:
The heart has superior and inferior vena cava, which carries de-oxygenated blood from the upper and lower regions of the body respectively and supplies this de-oxygenated blood to the right atrium of the heart.
The right atrium then contracts and passes the de-oxygenated blood to the right ventricle, through an auriculo-ventricular aperture (tricuspid valve).
Then the right ventricle contracts and passes the de-oxygenated blood into the two pulmonary arteries, which pumps it to the lungs where the blood becomes oxygenated. From the lungs, the pulmonary veins transport the oxygenated blood to the left atrium of the heart.
Then the left atrium contracts and through the auriculo-ventricular aperture (bicuspid calve) the oxygenated blood enters the left ventricle.
The blood passes to aorta from the left ventricle. The aorta gives rise to many arteries that distribute the oxygenated blood to all the regions of the body.
Therefore, the blood goes twice through the heart. This is known as double circulation.
Importance of double circulation:
The separation of oxygenated and de-oxygenated blood allows a more efficient supply of oxygen to the body cells. This efficient system of oxygen supply is very useful in warm-blooded animals such as human beings.
As we know, warm-blooded animals have high energy needs to maintain a constant body temperature by cooling themselves when they are in a hotter environment and by warming their bodies when they are in a cooler environment. Hence, they require more O2 for more respiration so that they can produce more energy to maintain their body temperature. Thus, the circulatory system of humans is more efficient because of the double circulation.
What is the function of platelets?
The loss of blood has to be minimised. In addition, leakage would lead to a loss of pressure which would reduce efficiency of the cirulatory system.
To avoid this, the blood has platelet cells which circulate around the body and plug these leaks by helping to clot the blood at the points of injury.
Write a short note on lymph.
Through the pores present in the walls of the capillaries some amount of plasma, proteins and blood cells escape into intercellular spaces in the tissues to form the tissue fluid or lymph. It is similar to the plasma of blood but colourless ans contains less protein. Lymph drains into lymphatic capillaries from the intercellular spaces, which join to form large lymph vessels that finally open into larger veins. Lymph carries digested and absorbed fat from intestine and drain excess fluid from extra cellular space back into the blood.
Differentiate between xylem and phloem.
Xylem:
- xylem transports water and minerals from the roots to aerial parts of the plant.
- On maturity, xylem exists as non-living tissue.
- Transportation in xylem is unidirectional.
- Structure of xylem is tubular with hard walled cells.
Phloem:
- Phloem transports food and organic nutrients such as sugar and amino acids from leaves to storage organs and growing parts of plant.
- Phloem exists as living cells.
- Transportation in phloem is bidirectional.
- Phloem is also tubular but with soft walled cells.
Differentiate between autotrophic and heterotrophic nutrition.
Autotrophic Nutrition:
- Food is synthesised from simple inorganic raw materials such as CO2 and water.
- Presence of the green pigment chlorophyll is necessary.
- Food is generally prepared during day time.
- All green plants and some bacteria have this type of nutrition.
Heterotrophic Nutrition:
- Food is obtained directly or indirectly from autotrophs. This food is broken down with the help of enzymes.
- No pigment is required in this type of nutrition.
- Food can be prepared all times.
- All animals and fungi have this type of nutrition.
Explain transportation of water in plants.
Transport of water:
Root pressure - At the roots, cells in contact with the soil actively take up ions. This creates a difference in the concentration of these ions between the root and the soil. Thus osmosis takes place. Water moves into the root from the soil to eliminate this difference. This means that there is steady movement of water into root xylem, creating a column of water that is steadily pushed upwards. The effect of root pressure in transport of water is more important at night.
Transpiration pull - Root pressure by itself is unlikely to be enough to move water over the heights that we commonly see in plants. Plants use another strategy to move water in the xylem upwards to the highest points of the plant body. Provided that the plant has adequate supply of water, the water which is lost through the stomata is replaced by the xylem vessels in the leaf. In fact, evaporation of water molecules from the cells of a leaf creates a suction which pulls water from the xylem cells of roots. The loss of water in the form of vapour from the aerial parts of the plant is known as transpiration. Thus, transpiration helps in the absorption and upward movement of water and minerals from roots to the leaves. It also helps in temperature regulation. During the day, when the stomata are open, the transpiration pull becomes the major driving force in the movement of water in the xylem.
What is the function of kidney?
- Removing excess water from the body (osmoregulation) and nitrogenous wastes (urea ans uric acid) from blood in the form of urine.
- Maintaining constant concentration of blood plasma.
- Regulating the pH of blood.
- Homeostasis.
Explain structure of nephron.
Each kidney is made up of thousands of tiny filtration units or tubules called nephron. It is the structural and functional unit of kidney.
Blood at high pressure travels into these by blood capillaries called glomerulus, which are surrounded by a cup-shaped capsule called the Bowman’s capsule.
The cup-shaped structure is followed by a long tubular structure. It is convoluted, twisted and known as Henle’s Loop. It finally leads to the collecting duct that collects the filtered urine.
