Chemical vs physical changes of state

Weathering describes the breaking down or dissolving of rocks and minerals on the surface of the Earth. Water, ice, acids, salts, plants, animals, and changes in temperature are all agents of weathering. Once a rock has been broken down, a process called erosion transports the bits of rock and mineral away. No rock on Earth is hard enough to resist the forces of weathering and erosion. Together, these processes carved landmarks such as the Grand Canyon, in the U.S. state of Arizona. This massive canyon is 446 kilometers (277 miles) long, as much as 29 kilometers (18 miles) wide, and 1,600 meters (1 mile) deep. Weathering and erosion constantly change the rocky landscape of Earth. Weathering wears away exposed surfaces over time. The length of exposure often contributes to how vulnerable a rock is to weathering. Rocks, such as lavas, that are quickly buried beneath other rocks are less vulnerable to weathering and erosion than rocks that are exposed to agents such as wind and water, As it smoothes rough, sharp rock surfaces, weathering is often the first step in the production of soils. Tiny bits of weathered minerals mix with plants, animal remains, fungi, bacteria, and other organisms. A single type of weathered rock often produces infertile soil, while weathered materials from a collection of rocks is richer in mineral diversity and contributes to more fertile soil. Soils types associated with a mixture of weathered rock include glacial till, loess, and alluvial sediments. Weathering is often divided into the processes of mechanical weathering and chemical weathering. Biological weathering, in whichliving or once-living organisms contribute to weathering, can be a part of both processes. Mechanical Weathering Mechanical weathering, also called physical weathering and disaggregation, causes rocks to crumble. Water, in either liquid or solid form, is often a key agent of mechanical weathering. For instance, liquid water can seep into cracks and crevices in rock. If temperatures drop low enough, the water will freeze. When water freezes, it expands. The ice then works as a wedge. It slowly widens the cracks and splits the rock. When ice melts, liquid water performs the act of erosion by carrying away the tiny rock fragments lost in the split. This specific process (the freeze-thaw cycle) is called frost weathering or cryofracturing. Figure 4.3 Frost Wedging Temperature changes can also contribute to mechanical weathering in a process called thermal stress. Changes in temperature cause rock to expand (with heat) and contract (with cold). As this happens over and over again. the structure of the rock weakens. Over time, it crumbles. Rocky desert landscapes are particularly vulnerable to thermal stress. The outer layer of desert rocks undergo repeated stress as the temperature changes from day Eventually, Lo outer night. layersflake off in thin sheets, a process called exfoliation. Exfoliation contributes to the formation of bornhardts, one of the most dramatic features in landscapes formed by weathering and erosion. Bornhardts are tall, domed, isolated rocks often found areas. in tropical Sugarloaf Mountain, an iconic landmark in Rio de Janeiro, Brazil, is bornhardt. a Salt also works to weather rock in a process called haloclasty. Saltwater sometimes gets into the cracks and pores of rock. If the saltwater evaporates, salt crystals are left behind. As the crystals grow, they put pressure on the rock, slowly breaking it apart. Plants and animals can be agents of mechanical weathering. The seed of a tree may sprout in soil that has collected in a cracked rock. As the roots grow, they widen the cracks, eventually breaking the rock into pieces. Over time, trees can break apart even large rocks. Even small plants, such as mosses, can enlarge tiny cracks as they grow. Animals that tunnel underground, such as moles and prairie dogs, also work to break apart rock and soil. Other animals dig and trample rock aboveground, causing rock to slowly crumble. Chemical Weathering Chemical weathering changes the molecular structure of rocks and soil.For instance, carbon dioxide from the air or soil sometimes combines with water in a process called carbonation. This produces a weak acid, called carbonic acid, that can dissolve rock. Carbonic acid is especially effective at dissolving limestone. When carbonic acid seeps through limestone underground, it can open up huge cracks or hollow out vast networks of caves. Carlsbad Caverns National Park, in the U.S. state of New Mexico, includes more than 119 limestone caves created by weathering and erosion. The largest is called the Big Room.. With an area of about 33,210 square meters (357,469 square feet), the Big Room is the size of six football fields. Another type of chemical weathering works on rocks that contain iron. These rocks turn to rust in a process called oxidation. Rust is a compound created by the interaction of oxygen and iron in the presence of water. As rust expands, it weakens rock and helps break it apart. Another familiar form of chemical weathering is hydrolysis. In the process of hydrolysis, a new solution (a mixture of two or more substances) is formed as chemicals in rock interact with water. In many rocks, for example, sodium minerals interact with water to form a saltwater solution. Hydration and hydrolysis contribute to flared slopes, another dramatic example of a landscape formed by weathering and erosion. Flared slopes are sometimes nicknamed "wave rocks." Their c-shape is largely concave rock formations a result of subsurface weathering, in which hydration and hydrolysis wear away rocks beneath the landscape's surfaceWeathering and People Weathering is a natural process, but human activities can speed it up. For example, certain kinds of air pollution increase the rate of weathering Burning coal, natural and petroleum releases chemicals such as nitrogen oxide and gas, sulfur dioxide into the atmosphere. When these chemicals combine with sunlight and moisture, they change into acids. They then fall back to Earth as acid rain. Acid rain rapidly weathers limestone, marble, and other kinds of stone. The effects of acid rain can often be seen on gravestones, making names and other inscriptions impossible to read. Acid rain has also damaged many historic buildings and monuments. For example, at 71 meters (233 feet) tall, the Leshan Giant Buddha at Mount Emei, China is the world's largest statue of the Buddha. It was carved 1,300 years ago and sat unharmed for centuries. An innovative drainage system mitigates the natural process of erosion But in recent years, acid rain has turned the statue's nose black and made some of its hair crumble and fall.

• Agriculture is growing of crops and keeping of animals. • People who practice agriculture are called farmers. • Agriculture is very important to the family. Benefits to the family • It provides food. • It provides money. • Agriculture gives us medicine. • It provides jobs. • Agriculture gives us transport and power. • It helps most families become self sufficient. • Farm tools are instruments used on farms to make work easier. • They are usually handheld and are used frequently when practicing agricultural activities. • Farm tools are light in weight, easy to handle and are suited to the strength of the farmer Name of tool Picture Use Watering can For fine watering of seed beds bucket Carrying manure, fertilizer,seed and ripe crops Name of tool Picture Use Sickle Cutting grass and harvesting of cereals like rice and wheat Slasher Cutting down tall grass and weeds USES OF FARM TOOLS Name of tool Picture Use Garden trowel Transplanting seedlings and making planting holes Hand fork Shallow cultivation of soil Aerating the soil USES OF FARM TOOLS Name of tool Picture Use Shovel Loading and offloading soil or manure into a wheelbarrow, scotch cart or truck Spade Digging and turning over of moist soil USES OF FARM TOOLS Name of tool Picture Use Garden fork Loosening and turn soil Garden line Marking straight ridges and garden beds USES OF FARM TOOLS Name of tool Picture Use wheelbarrow Moving items around the farm Items such as soil, mulch, animal feed. Etc Knapsack sprayer Spraying pesticides and herbicides Spraying fertilizers on crops. • An inventory is a record of the things that you have. • This is a list of tools issued out and tools received back and from whom Inventory of farm tools Inventory record sheets Created by Date Name of tool Sheet Tool numbenumber Description r Location Quantity Spade 1/15 Black,wooden handle Store room 2 SAFETY IN AGRICULTURE • Agricultural activities can be dangerous. • Hazards involved results in injury, disability and death of people and animals. • The hazards are usually caused by physical injury and chemical poisoning. Common hazards in Agriculture 1. physical injury These include: • Injury caused by accidents during use of farm tools, equipment and machinery. • Misuse and improper storage of farm tools and equipment. • Being kicked by animals. • Drowning in farm pond, pool or dam. Common hazards in Agriculture 2 . Chemical poisoning These include: • Spraying without protective clothing. • Eating or smoking when spraying chemicals. • Dumping toxic chemical left overs on land and in water. • Eating agriculture produces without prior permission from adults. • Pesticides, herbicides and fertilizers pollute water sources and kill animals. Chemical poisoning Ways of preventing common agricultural hazards 1. Wear protective clothing such as gloves, gumboots, respirator, hat and overalls. 2. Do not eat, drink or smoke when spraying. 3. Dispose off all chemical remains safely. 4. Bury or burn empty chemical containers and chemical left overs. 5. Wash thoroughly with running water and soap after using chemicals. 6. Do not spray during windy days. 7. Handle tools the right way. 8. Fence farm ponds and dams. Ways of preventing common agricultural hazards Climate and Landuse Seasons of Zimbabwe Seasons of Zimbabwe Definition of terms • A season is a time of the year with almost the same weather patterns. • Weather is the state of the atmosphere at a particular time at a particular place. • it is the daily condition of air around us. • Seasons are determined by rainfall and temperature. Seasons of Zimbabwe • There are four seasons in Zimbabwe , which are: 1.The rain season 2.Post rain season 3.Cool dry season 4.Hot dry season Seasons of Zimbabwe 1.The rain season ( summer) • It is also called the hot- wet season. • The season begins in mid November to mid March. • The period is rainy and hot. • Dams and rivers fill up. Seasons of Zimbabwe 2 . The post rain season ( autumn ) • It starts mid March – May • The days are bright and sunny. • The leaves change from green to red, orange, yellow or brown before falling. • In addition, there is less sunlight because the days are shorter. • It is the harvesting period of most crops. Seasons of Zimbabwe 3. The cold dry season ( winter ) • It begins mid May – mid August • The mornings, evenings and nights are very cold. • Has short days and long nights. Seasons of Zimbabwe 4 . The hot season (spring ) • It begins mid August – mid November. • The days are very hot with cool nights. • A season for trees to develop new shoots. Summer Activities Agricultural activities done during the rain season includes: • Ploughing and planting of summer crops for example maize, cotton. • Weeding • Pest and disease control • Applying fertilizers. • Weekly dipping of animals because ticks, lice and mites would be many. • Harvesting of summer crops • Preparing fireguards. A fireguard is a fire break. • Beginning of the planting of wheat, barley and oats. Winter Activities • Planting of winter crops such as wheat, barley and oats. • Harvesting and selling of summer crops continues. • Constructing frost barriers for frost sensitive crops such as tomatoes. • Vaccinating animals against blackleg. • Supplementary feeding of grazing animals. • Dosing of animals to kill internal parasites. Spring Activities • Shelling and threshing of grain crops. • Dry planting of summer crops. • Carrying manure to fields. • Ploughing and harrowing. • Making planting holes Soil Components •Soil is made up of 4 components: 1)Mineral matter 2)Organic matter 3)Soil water 4)Soil air

CHARACTERISTICS OF LIFE The world is filled with familiar objects, such as tables, rocks, plants, pets, and automobiles. Which of these objects are living or were once living? What are the criteria for assigning something to the living world or the nonliving world? Biologists have established that living things share seven characteristics of life. These characteristics are organization and the presence of one or more cells, response to a stimulus (plural, stimuli), homeostasis, metabolism, growth and development, reproduction, and change through time. Organization and Cells Organization is the high degree of order within an organism’s internal and external parts and in its interactions with the living world. For example, compare an owl to a rock. The rock has a spe- cific shape, but that shape is usually irregular. Furthermore, differ- ent rocks, even rocks of the same type, are likely to have different shapes and sizes. In contrast, the owl is an amazingly organized individual, as shown in Figure 1-2. Owls of the same species have the same body parts arranged in nearly the same way and interact with the environment in the same way. Copyright © by Holt, Rinehart and Winston. All rights reserved. ORGANISM (Barn Owl) ORGAN (Owl’s Ear) TISSUE (Nervous Tissue Within the Ear) CELL (Nerve Cell) Every living organism has a level of organization. The different levels of organization for a complex multicellular organism, such as an owl, are shown in the figure below. FIGURE 1-2 THE SCIENCE OF LIFE 7 All living organisms, whether made up of one cell or many cells, have some degree of organization. A cell is the smallest unit that can perform all life’s processes. Some organisms, such as bacteria, are made up of one cell and are called unicellular (YOON-uh-SEL-yoo-luhr) organisms. Other organisms, such as humans or trees, are made up of multiple cells and are called multicellular (MUHL-ti-SEL-yoo-luhr) organisms. Complex multicellular organisms have the level of orga- nization shown in Figure 1-2. In the highest level, the organism is made up of organ systems, or groups of specialized parts that carry out a certain function in the organism. For example, an owl’s ner- vous system is made up of a brain, sense organs, nerve cells, and other parts that sense and respond to the owl’s surroundings. Organ systems are made up of organs. Organs are structures that carry out specialized jobs within an organ system. An owl’s ear is an organ that allows the owl to hear. All organs are made up of tissues. Tissues are groups of cells that have similar abilities and that allow the organ to function. For example, nervous tissue in the ear allows the ear to detect sound. Tissues are made up of cells. A cell must be covered by a membrane, contain all genetic information necessary for replication, and be able to carry out all cell functions. Within each cell are organelles. Organelles are tiny structures that carry out functions necessary for the cell to stay alive. Organelles contain biological molecules, the chemical compounds that provide physical structure and that bring about movement, energy use, and other cellular functions. All biological molecules are made up of atoms. Atoms are the simplest particle of an ele- ment that retains all the properties of a certain element. Response to Stimuli Another characteristic of life is that an organism can respond to a stimulus—a physical or chemical change in the internal or external environment. For example, an owl dilates its pupils to keep the level of light entering the eye constant. Organisms must be able to respond and react to changes in their environment to stay alive. ORGANELLE (Mitochondrion) BIOLOGICAL MOLECULE (Phospholipid) ATOM (Oxygen) cell from the Latin, cella meaning “small room,” or “hut” Word Roots and Origins www.scilinks.org Topic: Characteristics of Life Keyword: HM60257 mb06se_bios01.qxd 5/18/07 10:37 AM Page 7 8 CHAPTER 1 Homeostasis All living things, from single cells to entire organisms, have mecha- nisms that allow them to maintain stable internal conditions. Without these mechanisms, organisms can die. For example, a cell’s water content is closely controlled by the taking in or releas- ing of water. A cell that takes in too much water will rupture and die. A cell that doesn’t get enough water will also shrivel and die. Homeostasis (HOH-mee-OH-STAY-sis) is the maintenance of a stable level of internal conditions even though environmental conditions are constantly changing. Organisms have regulatory systems that maintain internal conditions, such as temperature, water content, and uptake of nutrients by the cell. In fact, multi- cellular organisms usually have more than one way of maintain- ing important aspects of their internal environment. For example, an owl’s temperature is maintained at about 40°C (104°F). To keep a constant temperature, an owl’s cells burn fuel to produce body heat. In addition, an owl’s feathers can fluff up in cold weather. In this way, they trap an insulating layer of air next to the bird’s body to maintain its body temperature. Metabolism Living organisms use energy to power all the life processes, such as repair, movement, and growth. This energy use depends on metabolism (muh-TAB-uh-LIZ-uhm). Metabolism is the sum of all the chemical reactions that take in and transform energy and materials from the environment. For example, plants, algae, and some bacteria use the sun’s energy to generate sugar molecules during a process called photosynthesis. Some organisms depend on obtaining food energy from other organisms. For instance, an owl’s metabolism allows the owl to extract and modify the chemi- cals trapped in its nightly prey and use them as energy to fuel activities and growth. Growth and Development All living things grow and increase in size. Some nonliving things, such as crystals or icicles, grow by accumulating more of the same material of which they are made. In contrast, the growth of living things results from the division and enlargement of cells. Cell division is the formation of two new cells from an existing cell, as shown in Figure 1-3. In unicellular organisms, the primary change that occurs following cell division is cell enlargement. In multi- cellular life, however, organisms mature through cell division, cell enlargement, and development. Development is the process by which an organism becomes a mature adult. Development involves cell division and cell differen- tiation, or specialization. As a result of development, an adult organism is composed of many cells specialized for different func- tions, such as carrying oxygen in the blood or hearing. In fact, the human body is composed of trillions of specialized cells, all of which originated from a single cell, the fertilized egg. This unicellular organism, Escherichia coli, inhabits the human intestines. E. coli reproduces by means of cell division, during which the original cell splits into two identical offspring cells. FIGURE 1-3 Observing Homeostasis Materials 500 mL beakers (3), wax pen, tap water, thermometer, ice, hot water, goldfish, small dip net, watch or clock with a second hand Procedure 1. Use a wax pen to label three 500 mL beakers as follows: 27°C (80°F), 20°C (68°F), 10°C (50°F). Put 250 mL of tap water in each beaker. Use hot water or ice to adjust the tem- perature of the water in each beaker to match the temperature on the label. 2. Put the goldfish in the beaker of 27°C water. Record the number of times the gills move in 1 minute. 3. Move the goldfish to the beaker of 20°C water. Repeat observations. Move the goldfish to the beaker of 10°C. Repeat observations. Analysis What happens to the rate at which gills move when the temp- erature changes? Why? How do gills help fish maintain homeostasis? Quick Lab mb06se_bios01.qxd 5/18/07 10:37 AM Page 8 THE SCIENCE OF LIFE 9 Reproduction All organisms produce new organisms like themselves in a process called reproduction. Reproduction, unlike other characteristics, is not essential to the survival of an individual organism. However, because no organism lives forever, reproduction is essential for the continuation of a species. Glass frogs, as shown in Figure 1-4, lay many eggs in their lifetime. However, only a few of the frogs’ off- spring reach adulthood and successfully reproduce. During reproduction, organisms transmit hereditary informa- tion to their offspring. Hereditary information is encoded in a large molecule called deoxyribonucleic acid, or DNA. A short segment of DNA that contains the instructions for a single trait of an organism is called a gene. DNA is like a large library. It contains all the books—genes—that the cell will ever need for making all the struc- tures and chemicals necessary for life. Hereditary information is transferred to offspring during two kinds of reproduction. In sexual reproduction, hereditary information recombines from two organisms of the same species. The resulting offspring are similar but not identical to their parents. For example, a male frog’s sperm can fertilize a female’s egg and form a single fer- tilized egg cell. The fertilized egg then develops into a new frog. In asexual reproduction, hereditary information from different organisms is not combined; thus the original organism and the new organism are genetically the same. A bacterium, for example, reproduces asexually when it splits into two identical cells. Change Through Time Although individual organisms experience many changes during their lifetime, their basic genetic characteristics do not change. However, populations of living organisms evolve or change through time. The ability of populations of organisms to change over time is important for survival in a changing world. This factor is also impor- tant in explaining the diversity of life-forms we see on Earth today.

Nutrition Notes Nutrition- study of how your body uses food Process by which body uses nutrients How you look and feel Resist diseases and illness How you perform physically and mentally Nutrients: substances in food your body needs to grow, repair and supply energy to your body cells 6 Classes of Nutrients 1.Carbohydrates: 1 gram= 4 calories 2. Protein: 1 gram- 4 calories 3. Fats: 1 gram= 9 calories 4.Water 5. Vitamins 6. Minerals Calorie: measurement of energy in food Metabolism: Rate at which body burns energy(calories) Hunger: physical drive to eat Appetite: pshycological desire for food What influences your food choices: Foods you like Health Reasons Family and Culture Time & Money Advertising Emotions Friends Social Media: Modeling Nutrients Carbohydrates: your body’s main source of energy sugars/starches in food 45%-65% of diet #1 source of energy Simple: sugars converted to glucose= energy (fruits, dairy, honey, some manufactured foods) Complex: sugars linked together (starches) (grains, bread, pasta, beans, vegetables) Fiber: tough, indigestible carbohydrates Cleans our digestive system Prevents some types of cancer Prevents heart disease (fruits, vegetables, whole grains,nuts) 2. Protein: growth and repair of body tissues Made up of chemicals called “amino acids” Basic building material of all body cells (muscles, bones, skin, internal organs) Secondary source of energy protein(hemoglobin) attaches to oxygen in blood Functions as hormones regulating body functions 10-15% of diet *Body uses 20 Amino Acids found in food ( body produces 11 and 9 must come from diet) Essential amino acids: 9 amino acids body doesn't produce Complete Amino Acids: foods that contain all 9 essential amino acids ( animal products) Incomplete Amino Acids: food products that do not contain all 9 essential amino acids. Fats 15-25% of diet Secondary source of energy Blood clotting Controlling inflammation Maintains healthy skin/hair absorb /transport fat soluble vitamins Regulates body temperature Types of Fat Unsaturated: “good” fat Liquid at room temperature Can help fight heart disease (veg oil, nuts) Saturated: “bad” fat Solid at room temp Clogs arteries Causes strokes, heart attack, diabetes (animal products, meat, dairy) Cholesterol: waxy like fat substance found in meat products HDL: good type of cholesterol Body creates(liver) Creates cell wall, hormones, and vit D LDL: bad cholesterol- found in foods (clogs arteries) 4. Trans Fat: “one of the worst type of fats” Formed by a process called “hydrogenation”: adding Hydrogen molecules to unsaturated fats to make it more solid and resistant to chemical change. Vitamins A vitamin is a chemical compound that is needed in small amounts for the human body to work correctly. Vitamins are classified as either fat soluble (vitamins A, D, E and K) or water soluble (vitamins B and C). This difference between the two groups is very important. It determines how each vitamin acts within the body. The fat soluble vitamins are soluble in lipids (fats). Fat soluble vitamins can be stored in our body Water soluble vitamins must be taken every day Human body produces some amounts of Vitamin D & K

Physical Changes vs Chemical Changes - Starter Quiz

Physical vs Chemical Changes

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