Transcript Population
Unit 4 revision lesson Population Revision objectives • To go over Populations, Energy and Inheritance. • Everyone must be familiar with the content and describe what is required from them using the specification. • Most people should confidently answer short questions and aim for full marks. • Some people should answer the long exam questions confidently and aim to get full marks The specification • • • • • • • The next few slides show the specification. I have highlighted all the key words. I want you to make 3 columns. Confident to answer questions on this. Semi- confident. I pray this won’t come up. Write each of the keywords in each of the columns. The spec 3.4.1 The dynamic equilibrium of populations is affected by a number of factors. • A population is all the organisms of one species in a habitat. Populations of different species form a community. • Within a habitat a species occupies a niche governed by adaptation to both biotic and abiotic conditions. • Keywords and definitions. Investigating populations • A critical appreciation of some of the ways in which the numbers and distribution of organisms may be investigated. • Random sampling with quadrats and counting along transects to obtain quantitative data. • The use of percentage cover and frequency as measures of abundance. • The use of mark–release–recapture for more mobile species. Investigating populations 2 • In the context of investigating populations, candidates should • carry out experimental and investigative activities, including appropriate risk management • consider ethical issues arising when carrying out fieldwork, particularly those relating to the organisms involved and their environment • analyse and interpret data relating to the distribution of organisms, recognising correlations and causal relationships • appreciate the tentative nature of conclusions that may be drawn from such data. Variation in population size • Population size may vary as a result of the effect of abiotic factors • interactions between organisms: interspecific and intraspecific competition and predation. Human populations • Population size and structure, population growth rate, age population pyramids, survival rates and life expectancy. • Candidates should be able to • interpret growth curves, survival curves and age pyramids • calculate population growth rates from data on birth rate and death rate. • relate changes in the size and structure of human populations to different stages in demographic transition. In relation to exam questions • Lets look at some past papers! Population • Lots of 2 mark questions looking at the definitions of the key terms. • Look out for graph questions on predator prey relationships and competition. • Be ready to analyses graphs and relate your knowledge to the situation presented for the longer data questions. C D E A B With reference to the drawing, explain the meaning of the terms (i) community; ......................................................................................................... (ii) population. ...........................................................................................................................(3) (a) (b) Describe how you could use point quadrats to investigate the distribution of plants at the edge of a pond. (3) 1.(a)(i)All organisms living in a particular place; (ii) All the organisms of one particular species; Both examples illustrated with reference to drawing; 3 (b) Transect from water onto bank; Point quadrat frame placed at regular intervals; Record species touching points; Calculate percentage/process with kite diagram/ use statistical test to show..; max 3 Investigating populations • A mixture of marks and data related questions. • Can range from 6-15 mark questions. • Sampling techniques will most likely feature in the question. • Make sure that you can describe the different sampling techniques. • These questions are most likely to test your analytical skills so get ready to draw a conclusion. • Explain how a frame quadrat is used to find percentage cover of a species of plant in a habitat. (3) • Ground beetles are large black insects. The markrelease-recapture method can be used to estimate the ground beetle population on a roundabout. Describe how. (5) • Describe the techniques you would use to obtain reliable data in order to compare the sizes of the populations of the snail in the muddy area and in the area covered by vegetation. (3) • Describe one way in which you could place the quadrats randomly in a field. (2) Answer (a)suitable number of quadrats used; (many/ large number/ 10 minimum) count all the squares occupied (by the leaves of) one species; reference to randomising; description of a method of randomising any 3 b) 1Sample of ground beetles captured and counted (a); • 2 Released and second sample captured; • 3 Count total number of beetles (B) and number marked (b); • 4 Total population (A) estimated from the relationship ; • 5 Detail of method e.g. pitfall trap/marking with tippex; • 6 Refinement to ensure greater accuracy e.g. large number/ marking in position such that does not affect survival; 5 max c)use of large numbers of quadrats in each area (if number stated then 10+); random sampling method (e.g. grid + random numbers)/systematic sampling method (allow regular sampling along a transect); counting. OR (allow capture/recapture method mark and release; recapture; calculate proportion of marked snails in second sample) 3 D) Use of grids/coordinates; Table of random numbers; 2 Human populations • Will most likely get a 6/7 mark question. • Population demographic changes are common questions. • Expect you to make suggestions to what is causing change in population. • Graph interpretation questions are almost certain. • Make sure that you can calculate population change. Ok lets relate to exam questions 50 Rate per 1000 40 birth rate 30 20 10 death rate 0 1890 1900 1910 1920 1930 1940 1950 1960 1970 1980 1986 Mauritius is an island in the Indian Ocean. The graph shows the birth rate and the death rate for its human population between 1890 and 1986. Total population Population in 1890 1890 1900 1910 1920 1930 1940 1950 1960 1970 1980 1986 Year (ii) You would need to know the birth rate and the death rate in order to calculate the population growth in a particular year. What other information would you need? (1) (b) Before 1930, many deaths were due to infectious disease. Describe and explain one piece of evidence from the graph which supports this statement.(2) (c) Give one way in which the demographic transition shown in this graph differs from that which occurred in the United Kingdom. (1) (Total 6 marks) Answer (a) (i)Curve showing constant population until approx 1920; Increases after this and does not level out; 2 (ii) Immigration and emigration/migration;1 (b) Death rate prone to large fluctuations/spikes; Representing spread of disease during epidemics; 2 (c) Demographic transition in Mauritius occurs over shorter period of time/ Birth rate not stabilised at end/occurred earlier in UK; 1 [6] 90 The table shows some information about the populations of Japan and Nigeria. 80 70 60 50 Age / years (a) The diagram shows a population pyramid for Japan in 1999. 40 30 20 On the diagram, sketch the population pyramid as you would expect it to appear in 2015. 10 (2) Males Females Numbers Country Population Estimated Fertility in 1999/ population rate/ millions in 2015/ children per millions woman Japan 126.5 126.1 1.4 Nigeria 108.9 153.3 5.1 Life expectancy at birth/ years 80 Under-5 mortality/ deaths per 1000 4 50 187 (b) (i) Use information in the table to explain why the population of Nigeria is expected to increase to over 150 million by 2015. (2) (ii)Suggest and explain two factors that could result in the actual increase in the population of Nigeria being less than estimated. 1 ....................................................................................................... 2 ....................................................................................................... (2) (Total 6 marks) Answer (a) Diagram shows: narrower base; increase in numbers of older age groups/ straighter sides; 2 (b)(i) High fertility rate; higher than replacement rate of 2.0; not balanced by under-5 mortality; ref. to life expectancy greater than reproductive life; 2 max (ii) Disease/AIDS - affecting people of reproductive age increasing child mortality; shortage of resources/starvation - increasing as population rises; improved standard of living / contraception, so fewer children born effects of war, reducing number of parents, or causing starvation/shortage of resources; (Allow 1 mark for 2 factors, without explanations) 2 max [6]