Pdf download brackish water fishes neal monks

Total population This is the total number of individuals of a given species in the area under study. It is obtained by multiplying the species density by the total area of the ecosystem studied. It is used if the percentage of the quadrat area covered was estimated. If the quadrat is 1 m2, it is obtained by dividing the total percentage of ground that the species covered by the number of quadrats used.

Species frequency This is the percentage of quadrats in which the given species was found. These results can be recorded in tables and bar charts. Table 2. A representative sample of animals of a species is collected, the animals are counted and each one is marked, e. The animals are released back into the same area and given time to mix with the original population. A second sample is collected, counted and the number of marked organisms counted.

Abiotic factors are important in determining the types and numbers of organisms that exist in a given environment, i. Soil is a mixture of inorganic rock particles, water, air, mineral salts, organic matter and living organisms including plant roots, small animals and microorganisms.

Soil provides organisms living in it with water, oxygen, nitrogen and mineral nutrients. The smaller the soil particles, the more water held by capillarity and chemical forces rock particles and the higher the water content.

Clay: less than 0. The smaller the Silt: 0. Gravel: greater than 2. The larger the particles, the easier to determines the texture of penetrate and burrow through. Present as ions dissolved in soil water.

If the soil is too acidic or alkaline, mineral ions become less available. The optimum pH for most plants is 6. Humus is a absorbing and retaining minerals. Light is essential for plants to make food by photosynthesis and the rate of photosynthesis depends on light intensity. Light also synchronises activities of plants and animals with the seasons, e. At low temperatures, ice crystals may form in cells and damage them. At high temperatures, enzymes are denatured. Temperature affects the rate of photosynthesis and germination in plants and the activity of animals, e.

Water is essential for life. Chemical reactions in cells and most life processes need water in order to take place see page It is also essential for photosynthesis in plants.

It can affect the rate of transpiration in plants, the rate of evaporation of water from animals and the growth of vegetation, e. Oxygen is essential for aerobic respiration in almost all living organisms, carbon dioxide is essential for photosynthesis in plants and pollutant gases have a negative effect on living organisms. Aquatic organisms are affected by light, temperature, water availability and pollutants in the same way as terrestrial organisms.

They are also affected by other factors. Some are adapted to live in fresh water, some in salt sea water and others in brackish water, e. Revision questions 1 What is ecology? Distinguish between the biotic environment and the abiotic environment.

Discuss the importance of EACH of the following edaphic soil factors to organisms living in the soil: a water b air c mineral nutrients. Discuss the importance of EACH of the following climatic factors to living organisms: a light b temperature c atmospheric gases. Feeding relationships Food chains Organisms within any ecosystem are linked to form food chains based on how they obtain organic food. Energy from the sun enters living organisms through photosynthesis occurring in green plants, also known as primary producers.

This energy is incorporated into organic food molecules produced by the plants and is passed on to consumers through food chains. The levels of feeding within a food chain are referred to as trophic levels.

The prey is the organism that the predator eats, e. Predators are often the prey of other organisms and prey are often predators themselves. An apex predator is at the top of a food chain and has no predators, e. Table 3. The predator must evolve characteristics to catch its prey, e. At the same time, the prey evolves characteristics to avoid being eaten, e. If a predator overhunts its prey, the prey population will decrease and this will cause the predator population to decrease.

The prey population will then begin to increase again, which will allow the predator population to increase. This is known as biological control. It involves introducing a natural predator of the pest into the environment, e. Food webs Any ecosystem usually has more than one primary producer and most consumers have more than one source of food. Consequently, food chains are interrelated to form food webs.

They are essential for the recycling of chemical elements within all ecosystems see page They secrete digestive enzymes that breakdown complex organic compounds into simple organic compounds which they absorb. During this process, they release carbon dioxide and inorganic mineral nutrients in the form of ions, e. These can then be reabsorbed and re-used by plants. The parasite lives in or on the host and often has a vector or intermediate host which is unharmed by the parasite. Ticks on cattle cause damage to the hide, weakness, anaemia and tick paralysis.

The tapeworm absorbs digested food from the intestines and also gains shelter and protection. The infected person may suffer from abdominal pains, loss of appetite, weight loss and nausea. A pig is usually the intermediate host. After initially reproducing in the liver, the parasites enter red blood cells where they live and reproduce. It then recurs as the cells burst and the cycle continues resulting in a recurrent fever. The Anopheles mosquito is the intermediate host.

This causes reduced growth of the host. They usually grow high up on the branches where they are close to sunlight, have very little shade and are out of the reach of herbivores on the ground. They gain food scraps left by the sharks as they feed. The bacteria use nitrogen in the air in the soil to produce inorganic nitrogenous compounds. The plants gain nitrogenous compounds Root nodules of a leguminous plant which they use to manufacture proteins.

The bacteria gain food, which the plants produce during photosynthesis, and protection. The polyps gain food and oxygen as the algae photosynthesise. The algae gain carbon dioxide as the polyps respire, nitrogenous compounds excreted by the polyps, and protection. Termites are unable to digest the cellulose in the wood they eat; however, the protozoans can digest this cellulose into sugars.

The termites gain digested food. The protozoans are supplied with food and Coral polyps protection. Animals compete for food, space, a mate and shelter. Plants compete for light, water and minerals. Some of this energy is then released by the producers during respiration and some is passed on through food chains in the organic molecules. At each trophic level in a food chain, energy and biomass amount of biological matter are lost.

Some organic matter containing energy is lost in faeces and some is lost in organic excretory products, e. Some is used in respiration during which the stored energy is released and used, or lost as heat. The remaining energy containing organic matter is used in growth and repair, and is then passed on to the next trophic level when organisms are consumed. Organisms not consumed eventually die.

The organic matter in faeces, excretory products and dead organisms is decomposed by decomposers and they release the energy during respiration.

The different chemical elements that make up the bodies of all living organisms, mainly carbon, hydrogen, oxygen, nitrogen, phosphorus, sulfur and calcium, are continually cycled through these living organisms and the physical environment.

Decomposers are essential to the recycling of most of these elements. All living organisms have a continuous supply of water to keep their cells hydrated and to act as a solvent see page Aquatic organisms have a constant environment in which to live.

The cycling of carbon is essential to ensure that: Plants have a continuous supply of carbon dioxide to manufacture organic food by photosynthesis. Animals and decomposers have a continuous supply of organic food. The cycling of nitrogen is essential to ensure that: Plants have a continuous supply of nitrates to manufacture proteins. Animals and decomposers have a continuous supply of proteins.

Recycling of manufactured and other waste materials Recycling changes waste materials into new products. They include waste from the food industry, farmyard and garden waste, most paper and bagasse from the sugar industry. They include glass, plastics, rubber, construction waste, synthetic fabrics such as nylon, and metals such as iron, steel, aluminium, copper and lead. Also, different manufactured materials can have very different properties and they have to be sorted into their different types before recycling, e.

Revision questions 1 Some aphids were observed on the tomato plants in a garden and ladybird beetles 2 3 4 5 6 7 8 9 were seen feeding on the aphids. The ladybirds were, in turn, being eaten by dragonflies which were, themselves, being fed on by toads. Use this information to draw a food chain for the organisms in the garden. What are decomposers and why are they essential within any ecosystem? What is a symbiotic relationship?

Explain why food chains rarely contain more than four or five trophic levels. With reference to water, carbon and nitrogen, explain why it is important to continually recycle materials in nature. Suggest THREE difficulties encountered when trying to recycle manufactured and other waste materials in small countries such as the islands of the Caribbean.

This growth, together with improved standards of living, is having a profound effect on all other living organisms, natural resources and the environment in general. The impact of human activities on natural resources Human activities are having a negative impact on both non-renewable and renewable natural resources, and in many cases, these resources are being rapidly depleted. Renewable resources Renewable resources can be replaced by natural processes.

However, many plant and animal species are being overexploited such that their numbers are decreasing, in some cases to the point of extinction. This deforestation leads to: The loss of a habitat for plants and animals. The destruction of plants and animals living in the forests. Some of these may eventually become extinct. A reduction in photosynthesis resulting in a gradual increase in atmospheric carbon dioxide levels which is contributing to the greenhouse effect see page Disruption of the water cycle.

Soil erosion caused by the absence of leaves to break the force of the rain and roots to bind the soil. The loss of soil leads to: A reduction in the number of trees and other plants that can be grown. A reduction in the quantity of agricultural crops that can be grown. The negative impact of human activity on the environment Many human activities such as agriculture, industry, mining and disposal of waste have a negative impact on living organisms and the environment.

Pollution is the contamination of the natural environment by the release of unpleasant and harmful substances into the environment. Table 4. This causes other aquatic organisms to die, e. Acid rain decreases the pH of the soil, damages plants, harms animals, corrodes buildings, and causes lakes, streams and rivers to become acidic and unsuitable for aquatic organisms.

Burning fossil fuels in industry. Mining and quarrying. Cause lung damage and even at low concentrations they irritate the respiratory system, skin and eyes. This gas is extremely toxic, and even low concentrations irritate the eyes and respiratory system.

They include coral reefs, seagrass beds, rocky and sandy shores, mangrove swamps, estuaries and the open ocean. They are areas of land that are covered with water for either part or all of the year, and are usually found alongside rivers, lakes and coastal areas.

They include mangrove swamps, freshwater swamps, marshes and bogs. Many of these ecosystems are being polluted by untreated sewage, chemical fertilisers, pesticides, industrial waste, hot water, garbage and oil from oil spills. This pollution impacts negatively on both the overall health of the ecosystems and their aesthetic appeal.

This radiation causes warming of the Earth which is known as the greenhouse effect. Sun 3 Greenhouse gases absorb some radiation and radiate it back to Earth. This also warms the Earth. This warming, called global warming, is leading to global climate change.

The small island states of the Caribbean are extremely vulnerable to the effects of global warming due to their small size, fragile ecosystems, low-lying coasts, vulnerability to natural disasters, constraints on transportation and communication and, in some islands, limited fresh water supplies.

This can be achieved in a variety of ways. Replace renewable resources, e. Recycle resources, e. Re-use materials, e. Use materials made from renewable resources instead of non-renewable resources, e.

Reduce soil erosion, e. Set up breeding and aquaculture programmes for endangered and overexploited species, e. Set up nature reserves, national parks and marine sanctuaries. Put legislation in place to make it illegal to kill endangered species, e. Treat all sewage in sewage treatment plants and use the sludge as fertiliser and the water to irrigate crops. Collect and recycle or re-use all recyclable waste, e.

Compost all waste of plant origin, e. Use farmyard waste and waste from food industries to produce biogas. The growth of a population may be represented by a sigmoid growth curve see Figure This area is said to have reached its carrying capacity.

These limiting factors cause the death rate to increase and the size of the population stabilises at a particular level, i. If the death rate exceeds the birth rate, the population numbers decrease. If environmental conditions become favourable again, surviving members of populations begin to reproduce and population numbers increase once more. Human population growth The human population is currently in the phase of rapid growth.

It is growing at about 1. Revision questions 1 By reference to specific examples, differentiate between renewable and non-renewable 2 3 4 5 6 7 8 9 resources and explain how human activities are impacting on these resources.

How can the overuse of chemical fertilisers in agriculture affect aquatic environments? Outline some of the harmful effects of the following pollutants which are produced by burning fossil fuels in industry: a sulfur dioxide b carbon monoxide c smoke.

Explain how the improper disposal of garbage is harmful to human health and the environment. Discuss THREE reasons why marine and wetland ecosystems are of the upmost importance to the economies of many of the small island states of the Caribbean. An increase in greenhouse gases in the atmosphere is leading to global warming and global climate change. Outline FOUR consequences of global warming. Outline FIVE different measures that should be taken to help conserve and restore our environment.

Suggest FOUR factors that affect the growth and survival of populations. Their results are shown in Table 1 below. Suggest ONE reason for its presence in the pioneer zone. What piece of apparatus would they use?

Table 2 Food sources of organisms found in a woodland community Organism Food source Slug Leaves Caterpillar Leaves Earthworm Leaf litter Frog Slugs and caterpillars Blackbird Caterpillars and earthworms Grass snake Frogs Mongoose Grass snakes and blackbirds i Using only the information contained in Table 2, construct a food web for 3 marks the woodland community.

Total 15 marks Extended response questions 3 a Using a labelled diagram, explain how carbon is recycled in nature. Give THREE different reasons you could put forward to support this statement, other than the information 3 marks already used when answering part b above.

Total 15 marks Exam-style questions — Chapters 1 to 4 31 4 a Discuss THREE factors that have contributed to the dramatic increase in human 6 marks population growth over the past years. Total 15 marks 32 Exam-style questions — Chapters 1 to 4 5 Cells The cell is the basic structural and functional unit of living organisms. Some organisms are unicellular, being composed of a single cell; others are multicellular, being composed of many cells.

Cells are so small that they can only be seen with a microscope and not with the naked eye. Plant and animal cells All plant and animal cells contain structures called organelles which are specialised to carry out one or more vital functions, e.

Organelles are found within the cytoplasm of the cells and most are surrounded by one or two membranes. The cytoplasm and nucleus together are referred to as protoplasm. Supports the organelles and is the site of many chemical reactions nuclear membrane nucleoplasm chromatin thread nucleolus nucleus — surrounded by a double membrane.

Chromatin threads contain genetic information in the form of DNA which controls the characteristics and functioning of the cell. The nucleus is also essential for cell division mitochondrion — a rod-shaped organelle with a smooth outer membrane and folded inner membrane. Contains respiratory enzymes. Where respiration occurs vacuoles — small, membrane-bound compartments which may contain water, food, cell secretions or waste products Figure 5.

Supports and protects the cell, and gives it shape cell membrane chloroplast — a disc-shaped organelle surrounded by a double membrane. Contains many internal membranes, the green pigment called chlorophyll and photosynthetic enzymes. May contain starch grains. Where photosynthesis occurs starch grains — a food store mitochondrion vacuole — a large membrane-bound compartment containing cell sap, a solution of sugars, mineral salts, amino acids and waste products. Supports the cell when turgid.

May store food or cell waste vacuole membrane nucleus cytoplasm Figure 5. Do not have chloroplasts or chlorophyll. When present, the vacuoles are small and scattered throughout the cytoplasm and their contents vary. May contain glycogen granules as a food store. Can have a great variety of different shapes. Usually have chloroplasts which contain chlorophyll. Usually have one large, central vacuole which contains cell sap.

May contain starch grains as a food store. Have a regular shape, usually round, square or rectangular. The cells of prokaryotes lack a true nucleus and other membrane-bound organelles. Moreover, the brackish-water biotopes proved to be unique, and consist of a series of landlocked creeks, con nected to the sea by means of an underground salt water supply.

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