Human Influences On the Environment.
HUMAN INFLUENCES ON THE ENVIRONMENT What is deforestation? Deforestation is the removal of trees and natural vegetation from areas of dense forest or jungle. It is done primarily to obtain space that is essential for agriculture, fuel and building. However, there are many environmental issues that have derived solely from this mass extraction of wood. Wood has always been a primary forest product for human populations and industrial interests. Since wood is an important structural component of any forest, its removal has immediate implications on forest health. Intensive harvests can lead to severe degradation, even beyond a forests capacity to recover. When the soil has been stripped of its nutrients, farmers move further into the forests in search of new land. As forests are destroyed in this way, habitiats are removed from the animals living in them, therefore the biodiversity decreases. Forests also hold a big role in the water cycle as they release back the water that falls on them through transpiration. If trees are removed this may reduce the amount of water vapour that returns to the air, and may reduce rainfall either locally or in nearby regions which could inevitibly lead to drought. Trees also intercept the rain , lack of interception means that the water will not be slowed down on its journey to the ground. Therefore soil erosion and flooding can occur from
Biology lab - transpiration
AP Biology Lab 9: Transpiration Introduction Most of the water a plant absorbs is not used for a plant's daily functioning. It is instead lost through transpiration, the evaporation of water through the leaf surface and stomata, and through guttation, which is the loss of water from the vascular tissues in the margins of leaves. There are three levels of transport in plants: uptake and release of water and solutes by individual cells, short distance cell to cell transport at tissue and organ levels, and long distance transport of sap by xylem and phloem at the whole plant level. The transport of water is controlled by water potential. Water will always move from an area of high water potential to an area with low water potential. This water potential is affected by pressure, gravity, and solute concentration. Water moves into the plant through osmosis and creates a hydrostatic root pressure that forces the water upward for a short distance, however, the main force in moving water is the upward pull due to transpiration. This pull is increased by water's natural properties such as adhesion and cohesion. Transpiration decreases the water potential in the stele causing water to move in and pull upward into the leaves and other areas of low water potential. Pressure begins to build in the leaves, so to prevent downward movement, guttation occurs. Guttation occurs through leaf
Transpiration stream
Transpiration stream Transpiration is the loss of water from a plant by evaporation. Water is essential for plants as it is required for photosynthesis to produce glucose; all organisms derive their energy from the oxidation of glucose, minerals and ions are dissolved in water and bring them from the roots to other plant tissue that require the minerals. Also, water keeps the plant cool. The plant undergoes several processes in order for it to lose the amount of water through the lower epidermis of a leaf. Firstly, soil, is a very dilute solution of ions, which means a lot of water has been dissolved in to solution, and therefore the soil solution has a very high water potential. On the other hand the root hair cells have an insufficient amount of water molecules, resulting in root cells having low water potential. Root cells have a partially permeable membrane, which allows water to travel through them due to osmosis, where water travels from high water potential to low water potential. Root hair cells have a high surface area to volume ratio to efficiently absorb water. As water enters root hair cells, it has three routes for it travel along symplastic pathway, apoplastic pathway and vacuolar pathway. In the symplastic pathway water crosses the cellular membrane of root hairs and enters the cytoplasm of the cell, it travels between connecting cells through the
An experiment to show how water loss in leaves can vary.
An experiment to show how water loss in leaves can vary Introduction Transpiration is the movement of water from an area of high concentration to an area of low concentration in a leaf from out of the stomata. Mostly the stomata lie on the under side of the leaf but occasionally the stomata can lie on the top or on the stem of the leaf. Factors that increase the rates of reaction are: windy conditions, hot conditions, humid conditions and the rate of water being absorbed through the roots being smaller than the rate it is transpired. A couple of ways that you could decrease or prevent transpiration could be keeping the leaf in an airtight container so the water evaporated does not escape and the conditions surrounding the leaf are humid so the rate of transpiration would not be as great, another way could be to cover the stomata with a substance such as Vaseline so the water is physically prevented from escaping. I have chosen this as my preferred method for this investigation. Variables * Leaf sizes can affect the rate of reaction in two different ways either by the leaves having varying surface area or varying thickness e.g. some leaves are fleshier than others. * The petiole sizes can be different and the bigger the petiole, the bigger the water capacity the leaf can hold. * Varying amounts of Vaseline means that some leaves have differing strengths of barriers
An Experiment to Determine the Water Potential (Ψ) of a Plant Tissue, using Discs of Beetroot
An Experiment to Determine the Water Potential (?) of a Plant Tissue, using Discs of Beetroot Introduction Water potential (?) is the measurement of the ability of water molecules to move within a cell. A high water potential (?) is achieved when there is a high water concentration within a cell. The water molecules create an outward force on the cell membrane and wall, which makes the pressure within the cell high. Plant cells with a high water potential (?) become turgid, because of the cell wall's ability to stretch slightly to reduce the pressure within the cell. Animal cells do not have cell walls and therefore lack in the ability to reduce this pressure. If the water potential (?) in an animal cell becomes too great, the cell membrane will break and the cell will have burst under the pressure. The concentration of water in a cell is controlled by several factors: * Solute potential (?s) - If there is a higher water concentration in the cell than there is in the surrounding solution, water molecules will move out of the cell. This is because osmosis (the net movement of water molecules through a partially permeable membrane) is taking place. Osmosis ALWAYS involves water molecules moving DOWN the concentration gradient, from where they are in a high water concentration (where ? is close to 0) to where they are in a low water concentration(where ? is a more
transpiration lab
BIO LAB REPORT Comparing transpiration rates on different sides of a leaf Aim: To compare the rates of transpiration between the lower and upper surface of a leaf. Hypothesis: Leaf A will have the greatest change in mass, whereas leaf C will have the least change in mass. This is because leaf A is covered on the upper surface which will allow a lot of transpiration to take place. Leaf C will have the least evaporation taking place as the entire leaf is covered with Vaseline. Scientific theory: Transpiration is the evaporation of water from aerial parts of plants, especially leaves but also stems, flowers and fruits. Transpiration is a side effect of the plant needing to open its stomata in order to obtain carbon dioxide gas from the air for photosynthesis. Transpiration also cools plants and enables mass flow of mineral nutrients from roots to shoots. Mass flow is caused by the decrease in hydrostatic (water) pressure in the upper parts of the plants due to the diffusion of water out of stomata into the atmosphere. Water is absorbed at the roots by osmosis, and any dissolved mineral nutrients travel with it through the xylem. The rate of transpiration is directly related to whether the stomata are open or closed. The amount of water lost by a plant depends on its size, along with the surrounding light intensity, temperature, humidity, wind speed, and soil water supply.
The effect of temperature change on the activity rate of Trypsin.
The effect of temperature change on the activity rate of Trypsin Introduction This piece of coursework will look at what effect temperature has on the activity of Trypsin and which temperature Trypsin works best at. It was predicted that the milk would turn transparent quickest at the 40 oC temperature level, as the enzyme in a Trypsin is found in human bodies. The normal human body temperature is around 37 oC so the activity of the enzyme would work best at this temperature. Method A total mixture capacity of 10ml mixture Trypsin and milk, of 5ml of each, 5ml syringes were used to get the exact amount each time. The temperature range of 60 oC to use for the experiment, between 10 oC and 70 oC using 10 oC increments. A water bath was used to control the temperature of the mixture. Hot water from a kettle was used to heat up the Trypsin and milk mix, and ice was added to the water bath to cool it down when necessary. Trypsin was added to the milk and see how long it took for the milk to become transparent. A piece of paper was placed behind the test tube with writing on it. When the writing was clearly readable, the elapsed time on the stopwatch was recorded. The temperature of the water bath was controlled by adding ice or hot water to it. Separate test tubes were used for the Trypsin and milk in the water bath, these were left for 1 minute so that the contents
Investigate the relationship between wavelength of light and the rate of photosynthesis using pondweed.
George Bourne Photosynthesis coursework 3/10/02 Problem Investigate the relationship between wavelength of light and the rate of photosynthesis using pondweed. Background information * Photosynthesis: Photosynthesis is a process where by plants produce their own food using carbon dioxide and water in the presence of light absorbed by chlorophyll. Carbon Dioxide+ Water Glucose+ Oxygen Sunlight Chlorophyll 6CO2 +6H2 O C6H12O6 +6O2 The rate of photosynthesis may be affected by things called limiting factors, such as: * Temperature, * Carbon dioxide, * Light * Water. * The temperature of a surrounding area affects photosynthesis; therefore it's a limiting factor. An increase of 10 c can double the rate of photosynthesis, but above 40 c photosynthesis will stop because the enzymes, which chemically react during photosynthesis, will be denatured. Different plants have different temperatures at which they grow best, this is know as their optimum temperature. The greater the quantity of carbon dioxide in the surrounding area around a plant, the faster the plant will photosynthesise. The brighter the source of light, the faster the rate of photosynthesis. Pond water produces bubbles in light and this information can be
Investigate the effect of huddling on heat loss.
Huddle investigation PLANNING A Aim: to investigate the effect of huddling on heat loss Hypotheses: . That the larger the huddle, the smaller the amount of heat lost. That is, an organism (test tube) on its own will lose more heat than if it were huddled in a group. In an experiment using test tubes, this will be supported by data which shows that a test tube by itself will lose more heat in the same amount of time than if it were in a huddle. 2. The temperature loss should decrease proportionally as the size of the huddle grows. 3. Also, the organism (test tube) in the centre of the huddle will lose less heat than an organism or test tube on the outside of the huddle. The reasoning behind this hypothesis is that as the huddle group grows in size, the amount of exposed 'surface area' will be reduced per test tube. Although in practice not every test tube is exposed, theoretically, this is a way of comparing huddles. Also, in a huddle of many organisms, or test tubes, if there is a centre test tube which is not 'exposed', it will be warmer than those on the periphery of the huddle. This hypothesis can be supported by data collected in the experiment by measuring the temperature of the centre of the huddle and the periphery of the huddle. The centre will be warmer because it has no surface area exposed to the outside. Huddling is a behavioural adaptation
An Investigation into the Effects that Different Light Intensities have on the Speed of Woodlice:
An Investigation into the Effects that Different Light Intensities have on the Speed of Woodlice: Introduction: Woodlice are one of the easiest terrestrial arthropods to obtain in large numbers throughout the year. Porcellio scaber, the most common species is not difficult to identify with the naked eye, and is large enough to be handled without employing special techniques. Their behaviour is relatively simple yet providing perfect examples of kinesis and taxis. i A species, which shows taxis, can orient the direction of their movement with respect to the source of an external stimulus whilst kinesis is a steady-state dependence of the movement velocity on the stimulus intensity.iii Thus it is clear that kinesis will be the important response in my investigation as I am not concerned with the stimulus direction. Woodlice lack a waxy cuticle on their exoskeleton and have a high surface area to volume ratio. This means that they are prone to desiccation. As a result, much of their behaviour is concerned with reducing water loss. Woodlice will therefore tend to congregate in more humid, cooler and darker regions where their water loss will be lower.ii Although light does not affect the physiological state of woodlice in the same way as humidity and temperature, it plays a very important part in woodlice behaviour. Woodlice have a negative photokinesis- they move faster as
