The environment can be defined as the surroundings in which as organism lives, including the climate, the physical and chemical conditions of its habitat and its relationship with other living things. Given the above understanding, it is therefore important that the right environment factors are in existence for some chemical reactions to take place. In the absence of optimum environmental factors, organisms would be compelled to adapt themselves to the prevailing environment. Cellular respiration and photosynthesis are two important chemical reactions for which the environment is of paramount importance.
Photosynthesis is the process by which green plants synthesize organic compounds, primarily sugars, from carbon dioxide, and water using sunlight and chlorophyll. 6 CO2 + 6 H2O C6H12O6 + 6 O2 Respiration is the process by which plants and animals metabolically break down organic compounds, mainly carbohydrates to release energy for use such as in the bodily processes, such as active transport. It can be either aerobic or anaerobic. Aerobic meaning respiration requires the presence of oxygen so as to take place.
Oxygen is taken by the cell and CO2 out through diffusion or active transport. The carbon dioxide and water produced are used by plants during photosynthesis. C6H12O6 + 6 CO2 6 H2O + 6 CO 2 + ENERGY In anaerobic respiration sugar is broken down to produce ethanol in plants and lactic acid in animals. C6H12O6 2 CH3CH2OH + 2CO2 +ENERGY C6H12O6 2CH3CH(OH)COOH + ENERGY The effects of environment on photosynthesis: Depending on the nature of the plant or photosynthetic organism, too much light may be harmful as well as too little light.
No light at all hinders the light conversion stage of photosynthesis from taking place. Prolonged absence of light may lead to yellowing and consequent death of the plant. This is due to lack of food. Light intensity influences the manufacture of food and development of stem, leaf colour and flowering in plants. An increase in light leads to an increase in the rate of photosynthesis, propionately until the light intensity reaches 10000 lux after which there is no effect. Some plants tend to grow elongated stems with the aim of reaching light faster. Other plants grow towards the source of light. . g. plants growing in a house grow towards the windows. Plants growing in the thick forests survive by climbing on taller stronger trees to get to sunlight above.
Others grow dark green leaves for maximum light absorption. E. g. the philodendron plant. When plants receive less light (eg when days are shorter) they tend to shed some leaves to reduce the us of energy and increase storage. Cordial temperature at which photosynthesis can be carried on have a minimum and maximum and optimum, and vary with species. The minimum may be as low as 0c in some artic plants.
The optimum for most plants is between 20c and 22c. It may be as high as 45c e. g. the laurel cherry. Too high temperature may increase the rate of water absorption by the plant. This is because the plant has to lose a lot of water through transpiration, to cool itself. Too high temperatures cause drying up of most common plants since their cells get denatured. Succulent plants e. g. cactus have thick leaves with large cells that store water from infrequent rains. They are also covered with a thick cuticle which greatly reduces the evaporation of water.
Some plants e. g. thorn trees modify most of their leaves to thorns, to reduce the surface area for transpiration. Some plants such as the golden bells store water and food in underground bulbs and their leaves dry up completely during prolonged period of intense heat and sprout again during the season of reduced heat intensity or wit increase in water supply. Plants growing in areas that experience extreme cold temperature grow winter buds on trees and shrubs which protect the growing part if the plant from freezing.
Plants such as the orchids cover their aerial roots with a thick whitish layer of cells (vela men), which holds available water. Many trees and shrubs shed their leaves during summer when temperature is high to reduce the rate of transpiration. Increase of water to a certain point may increase the rate of photosynthesis. Sufficient supply of water provides more favorable conditions for photosynthesis. Therefore greatly increasing the rate of growth. Too much water for most common plants may clog the roots preventing aeriation of the roots thus cause rotting death.
Some plants grow only under water while others do best with little water e. g. the orchids. 1)Plants growing in dry areas develop very long roots which grow deep in search of water below the water table level. 2) Many plants shed their leaves during prolonged drought. 3)Some plants such as thorn tree modify their leaves in thorns. 4)Development of smaller leaves during water shortages and larger ones when water is available. 5)Storage of water in the stem, roots and or leaves when water is scarce. 6)Developing large leaves to help the plant to bloat.
E. g. water hyacinth. 7)Forming a network roots for support e. g. mangrove tree. An increase in CO2 is hardly noticed until it is 20 – 30 times the normal amounts, during which the rate of photosynthesis noticeably changes. On the other hand, plant denied of CO2 cannot carry out photosynthesis and therefore yellows and dies. One point to be noted is that increase in CO2 affects the temperature, which also affects the plants as we discussed. The effects of environment on aerobic respiration: Low temperature increases the rate of respiration.
This is because the body has to make more energy ATP to heat it up and prevent freezing. High temperature has no direct effect on aerobic respiration however the cells will die and therefore no respiration will take place or will not be needed. Mammals in the sea have large layers of fat, which keeps them warm during nights. Mammals in the artic region hibernate during winter to conserve energy. Cold-blooded animals reside only in warm places and try to go under shade when it is very hot. An increase in the amount of O2 causes an increase in aerobic respiration.
However, too much of O2 causes O2 poisoning since the high affects the body reactions. Too much CO2 will cause the body to acquire H+ due to lack of oxygen ions for the redox reaction and lead to acidity in the cells. Therefore increasingly reduced and may be fatal. 1)Sea mammals dive after taking in air and then the cardiac frequency drastically decreases (brandycardia) and the arterials of all vital organs constrict so that O2 can be delivered to the vital organs. 2)Sea mammals also have a very huge lung so that they can go on for some time with having to come up for air every minute. )Humans living in high altitude regions have more red blood cells so that they can take in more oxygen every time they breathe in. 4)
Plants living under water have special roots which absorb oxygen from the water so that they can respire. The higher the humidity the harder it seems to breath because of the increases ratio of water to other gases in the air. With increased ratio of humidity to O2, respiration is reduced since the amount of O2 is reduced. The body acquires large number red blood cells to transport oxygen all around the body.
The most important is that a lot of sweating takes place in animals and transpiration in plants. The effect of the environment on anaerobic respiration: Anaerobic respiration involves enzymes. These enzymes work best at a optimum temperature of 37c. Too much of heat may denature the enzymes thus slowing down the respiration process. In bacteria or other microorganisms high temperatures might kill them. Enzymes after some time get adapted to different temperature. This is a part of evolution. The presence of oxygen hinders anaerobic respiration in higher level organisms.
However many microorganisms are not affected by the presence or absence of oxygen as they have only anaerobic respiration. The importance of anaerobic respiration is that is a substitute for aerobic respiration. This is used in many industries. E. g. dairy industry. The law of conservation of energy states that energy can neither be destroyed nor created and to confirm to it we have these biological chemical processes, which are interrelated. The end product of photosynthesis is the raw material of respiration. The byproducts of respiration are used in photosynthesis.
CO2 + H20 C2H12O6 + O2 1)Roberts M. B. V, Biology – A Functional Approach. 3rd edition, Buttler & Tanner ltd. Gr. Britain. 1982 2)Hall D. O and Rao K. K, photosynthesis 5th edition, Cambridge university press. Gr. Britaon. 1996. 3)Enger D Eldon and Ross C Fredric, concepts in biology 8th edition. W. M. C Brown publishers 1997. 4)Audesirk and Audesirk, Biology: Life on earth, Macmillan paublishers, new york. 1989. 5)Readers digest encylopedia of essential knowledge. 6)Cecie starr, Biology, concepts and application.
