Shipwrecked summary Name _______________________ Biodiversity Biodiversity is the term used to describe the range of living organisms that are found on the planet. Human activities can have negative impact on Biodiversity by decreasing it. Examples of such activity include: Many human activities can affect the biodiversity in an area. 1. Habitat destruction destroying the homes of animals 2. Over-fishing catching more fish than needed 3. Deforestation cutting down too many trees 4. An oil spill oil being released into the sea All of these would DECREASE biodiversity as the numbers of animals and plants would DECREASE Interdependence An animal that hunts other animals is a predator. What it hunts is its prey. The feeding relationship can be shown in a food chain. Food chains are joined together to form food webs. Food chains and food webs show how energy is transferred from one organism to another. Each stage is linked by an arrow. Every food chain/food web starts with a producer (green plant). They make their own food through the process of photosynthesis. Energy from the sun is used to form a chemical energy, which gets passed to the consumer when it is eaten. Food chains and food webs describe the interdependence of living things. The removal of organisms from either a food chain or a food web can have a consequence on the other organisms in that chain or web. If one organism is removed from a food web, the other animals and plants in the food web can also be affected. Shipwrecked summary In the food web above, if the slugs were all removed, then the thrush numbers would DECREASE due to a lack of food. The numbers of grass could INCREASE as they are no slugs eating it. Natural hazards Natural hazards affect all populations. Floods, cyclones, droughts, fire and heat waves are related to climate change, deforestation and the world’s weather systems. Earthquakes, volcanoes and tsunamis are all the results of movements in the Earth’s crust. They have the greatest impact in a areas where the population is high. Such hazards will have a wide variety on biodiversity. With habitats being destroyed, animals and plants will lose shelter, food, and reproductive mates. These all affect the survival rates of the species. Sampling techniques and abiotic factors If we want to learn about a particular habitat, we need to carry out an investigation. This involves collecting and identifying organisms and measuring the physical conditions. It is not possible to collect all the organisms within a habitat, so we take samples. A quadrat is used to take plant samples, it is thrown randomly and the number of squares which contain the plant are counted. A pitfall trap is used to take sample of small organisms that live on the ground. An abiotic factor is a physical factor such as light, moisture, pH or temperature. Abiotic factors influence the organisms living in a habitat. Shipwrecked summary Abiotic factor Light intensity Technique for Possible source of Ways of minimising measurement error error Use a light meter, Operator may shadow Stand to one side of direct the light the light sensitive the light meter so sensitive panel panel. that there is no towards the light. shadow Take a reading Soil moisture Use a soil moisture Moisture from a Wipe the probe in meter, push the previous reading on between readings. probe gently into the the probe. soil. Take a reading. Adaptations Animals and plants are adapted to where they live. This means that they have certain inherited features that allow them to survive in a habitat. For example, fish are adapted to living underwater. They have gills to take in oxygen out of the water, fins to swim with and streamlined bodies to help them move easily through the water. A CAMEL has broad feet to stop it sinking into the sand EAGLES have good eyesight to hunt prey DEER have good hearing to listen out for predators In birds, the shape and size of their beak is matched to the type of food they eat. 1. Very small beaks will be used to eat small insects or seeds e.g a CHAFFINCH 2. Birds with sharp pointed beaks will often eat other animals e.g a HAWK 3. Birds with very large beaks can eat a lot of fish very easily e.g a PELICAN Shipwrecked summary Animal behaviour Animals can learn behaviour, ranging from being trained to perform extraordinary things (guide dogs) to animals being trained to entertain us (whales and dolphins). Hungry snails will follow a trail of flour and water that is painted onto a Perspex sheet. This is of survival value as the snail will move in the direction of a food source. An animals learning is influenced by a number of internal and external factors. Animals exposed to a continual harmless stimulus will eventually stop responding to the stimulus, a process known as habituation. Animal behaviour can be studied experimentally by investigating how they respond to the environment. Animal Stimulus Response Importance to animal Woodlouse Moisture Moves towards moisture Need to keep breathing system moist to be able to breathe Blowfly maggot Light Moves away from light Needs to stay in dark places to obtain food and protection from predators Hedgehog Decreasing Hibernation day length Cockroach Darkness Conserves energy when food is in short supply Becomes active Less chance of being caught by predators Swallow Decreasing Migration Enables it to obtain food day length Micro-organisms and industry Living cells such as bacteria and yeast can be used to produce a range of useful substances. Yeast is used to make bread and wine. Yeast can respire without oxygen (anaerobically) and this process is called fermentation. Shipwrecked summary Carbon dioxide makes bread dough rise and alcohol is used to produce wine, beer and all other alcoholic beverages. Bacteria is used in the manufacture of both cheese and yoghurt. Bacteria feeds on the lactose sugar in milk and converts it into lactic acid. This causes the milk to curdle and change consistency and taste, forming yoghurt. To make cheese an enzyme called rennet is then added to the yoghurt like substance. Rennet used to be obtained from the lining of calves stomachs but is now manufactured differently. Rennet causes the milk proteins to clot forming curds which go on to form cheese when salt is added and the solid is allowed to mature. Respiration Fermentation Plant reproduction To reproduce sexually some plants produce flowers. The flowers contain the sex organs. Shipwrecked summary Many plants can reproduce in way that only involves one parent and no seed formation. This is called asexual reproduction and does not involve the formation of sex cells. The parent plant produces new cells that separate from the parent and become new plants. Commercial plant growth When plants are grown commercially growers are always looking for ways to speed up the growing process. One of the ways in which they do this is through the use of polytunnels and another is the use of rooting powders. Germination Germination is the development of a new plant from the embryo plant in a seed. Seeds need Water, Oxygen and Warmth to germinate. All of these factors can affect the rate of germination as can competition when many seeds are planted together or too close together. Photosynthesis Shipwrecked summary Photosynthesis is the process where green plants trap the light energy from the sun using the green pigment chlorophyll in their leaves and convert it into chemical energy in the form of glucose. The glucose that is not required is converted into the storage carbohydrate starch. To prove a plant is photosynthesising it can be tested for starch. We can measure the rate of photosynthesis by how much oxygen is produced in a given time. There are three factors that can limit the rate of photosynthesis, we call them limiting factors. They are: Light intensity Carbon dioxide concentration Temperature This is often shown in a graph. Nitrogen cycle The element nitrogen is recycled through all ecosystems. Nitrogen is essential to the survival and chemistry of all living things because it is found in all proteins. The nitrogen cycle involves a series of chemical reactions that transfers nitrogen between the non-living environment and living things. Shipwrecked summary Fertilisers Nitrogen can be found present in soil in the form of nitrates. Plants can absorb nitrates through their roots and use the nitrates for growth. Therefore, an increase in nitrate concentration in soil can increase the growth of plants. Nitrates can be found in fertilisers to encourage plant growth. Other minerals are found as well. Natural fertilisers include manure and growing plants like clover which can then be ploughed back into the soil. Mineral Importance to plant growth ‘N’ Nitrogen For leaf growth ‘P’ Phosphorus For root growth ‘K’ Potassium For growth of fruit and flowers Excess nitrates however can cause pollution in an environment, and cause the growth of unwanted plants, i.e. weeds and algae. Shipwrecked summary Farmers make use of fertiliser to increase the growth of their crops, however, improper use of them can have a negative effect on the environment. Fertilisers can be a source of pollution. Excess fertilisers used by farmers are washed off in to rivers and underground water sources. Eutrophication is the main environmental hazard associated with fertilisers. Excess fertilisers cause the nitrates levels in rivers to increase and encourage the growth of algae. When the algae die the bacteria feed on them using up all the oxygen which means that the other organisms suffer and die from oxygen deprivation.