S104 Exploring science Tutor-marked assignment 05 February 2011 presentation Covering

09 Jun S104 Exploring science Tutor-marked assignment 05 February 2011 presentation Covering

S104 Exploring science

Tutor-marked assignment 05
February 2011 presentation
Covering:

Book 5 Life

Cut-off date:

Thursday 14 July 2011

Introduction
This tutor-marked assignment (TMA) will contribute 12% towards your overall
module score.
Remember to show your working in all calculations.
Information about how to submit your TMA is given in the Assessment Handbook
(which you can access via StudentHome) and also on the Assessment page of the
S104 website.
You will receive feedback from your tutor on how well you have demonstrated
the learning outcomes listed for each question.

Question 1
We suggest that you tackle this question after you have studied Book 5,
Chapters 1–3.
This question carries 12% of the marks for this assignment. It will be marked
according to how well you demonstrate in your answer the following learning
outcomes:
Ky4

use information technology to learn and communicate, in particular,
access resources via the internet and contribute to electronic group
discussions

C2

apply knowledge and understanding of scientific concepts to address
familiar and unfamiliar problems and their contribution to informed
debate about topical issues
In Book 5, Activity 3.1 your tutor group collaborated to research several different
primate families. Using the information gathered by your tutor group, decide
which of the primate species investigated you would prioritise for conservation
action and explain why. (We expect you will be able to do this in 300–400
words.)
You will need to consider in your answer the combination of the factors
researched in the tutor group forum, namely the phylogenetic importance of the
species (and/or the primate family it belongs to), the geographical range and
habitat and any current specific or non specific threats your species is facing –
which may or may not be reflected in the current International Union for
Conservation of Nature (IUCN) red list status.
In Book 4, Activity 17.1 you accessed a journal article via the Open University
Library and were shown how to cite the source of journal references in the text
and then give the full details in a list of references at the end. For your answer to
this TMA question it is important that you reference the sources of any

Copyright © 2011 The Open University

WEB 02098 4
7.1

information you use to help you come to your decision about conservation action.
You should therefore use the following guidelines to help you reference any web
documents or organisational websites that you accessed to help you answer this
question. Your reference should be explicit enough to allow your tutor to find the
same website and check your information.
Referencing web documents
You should use the following format when referencing documents from the web:
Author’s surname and initials, year of publication (in brackets), title of
document, ‘available from’ information such as the web address, and the date
you accessed the site. For example:
Spitzer, K.L., Eisenberg, M.B. and Lowe, C.A. (1998) Information literacy:
essential skills for the information age [online], Syracuse, NY: ERIC
Clearinghouse on Information and Technology, Syracuse University (ED 427
780), available from: http://ericit.org/toc/infoliteracytoc.shtml (Accessed 28
October 2003).
The text citation should be given as: (Spitzer et al., 1998) or Spitzer et al. (1998)
state …
Another example (which references an organisational website rather than a
specific author) is:
Open University Library (January 2005) Welcome to the Open University
Library, available from: http://library.open.ac.uk/ (Accessed 2 February 2006).
The text citation should be given as: (Open University Library, 2005) or Open
University Library (2005) states …

Question 2
We suggest that you tackle this question after you have studied Book 5,
Chapters 5 and 6.
The question carries 28% of the marks for this assignment. It will be marked
according to how well you demonstrate in your answer the following learning
outcomes:
Kn1

knowledge and understanding of the importance to the cell/organism of
metabolic processes

C1

describe, analyse and interpret scientific information and data presented
in a variety of ways, including texts, tables, graphs, diagrams and
figures, numerical and mathematical descriptions, computer-based media

Ky2

process and present data using appropriate qualitative and quantitative
techniques and methods of presentation (including graph plotting)

(a) Figure 1 shows three graphs which individually illustrate the effect of
increasing the temperature, substrate concentration or enzyme concentration
on the rate of hydrolysis of starch to maltose by the enzyme amylase.

2

rate of reaction

rate of reaction

rate of reaction

A

B

C

Figure 1 The effect of increasing temperature, substrate concentration, or
enzyme concentration on the rate of hydrolysis of starch to maltose by the
enzyme amylase.
For each graph in Figure 1, describe how the rate of reaction changes in response to
the increase in the factor investigated and deduce which of the factors A, B and C
are the most likely to represent:
(i) temperature
(ii) substrate concentration
(iii) enzyme concentration (when the substrate is unlimited)
Using your knowledge of how enzymes work, explain the reasoning behind each
of your answers. (We expect you will be able to do this in no more than 350
words in total.)
(b) Table 1 shows the results of an experiment looking at the effect of
temperature on:
„

the production of sugars as a result of photosynthesis and

the use of sugars in the process of respiration in the leaves of a plant

growing in a constant high light intensity.

„

Table 1

Effect of temperature on the rate of sugar production or use.

Rate of sugar production or use /arbitrary units*
Temperature/°C

Sugar production in
photosynthesis (high
light intensity)

Sugar use in
respiration

0

0

2

5

36

4

10

42

5

15

72

6

20

80

8

25

48

16

30

12

30

35

0

20

40

0

Net gain of sugar
(negative value
shows net loss)

16

* Arbitrary unit: a relative unit of measurement which allows comparison of
experimental results.

3

(i) Using the data given in Table 1 calculate the net gain or loss of sugar at
each temperature and enter your data into Table 1 under the appropriate
heading. You may do this either by copying the completed Table 1 into
your TMA or by completing the electronic version of Table 1 available
on the Assessment page of the S104 website and including this with
your TMA.
(ii) Plot the data from Table 1, by hand, on to a single graph to show the
effect of temperature on:
„

sugar production during photosynthesis

„

sugar use during respiration and

the net gain or loss at each temperature.
(You should submit your graph as part of your assignment. For advice on
how to submit a hand-drawn graph via the eTMA system please consult
the S104 website. If you will have difficulty producing a graph by hand
please contact your tutor for advice.)
(iii) Describe and explain the effect of temperature on the net gain or loss of
sugar in this plant as shown on the graph you have plotted. From your
graph, estimate the temperatures at which the rate of sugar production
and use are equal and include this in your answer. (We expect you will be
able to do this in 150–200 words in total.)
(iv) Using your understanding of photosynthesis and respiration explain how
and why the net gain and loss of sugar differs between the day and night
hours in a plant growing in a greenhouse kept at a constant temperature
of 20 °C. Your explanation should include references to ATP and
NADP.2H. (We expect you will be able to do this in 120–150 words.)
„

Question 3
We suggest that you tackle this question after you have studied Book 5, Chapter 7.
The question carries 20% of the marks for this assignment. It will be marked
according to how well you demonstrate in your answer the following learning
outcomes:
Kn1

knowledge and understanding of food webs and energy flow through
ecosystems

C1

describe, analyse and interpret scientific information and data presented
in a variety of ways, including texts, tables, graphs, diagrams and
figures, numerical and mathematical descriptions, computer-based media

Ky1

use mathematical skills appropriate to the study of science at this level
(algebra and arithmetic)

Ky2

process and present data using appropriate qualitative and quantitative
techniques and methods of presentation

Throughout the calculation in this question you should show all of your
workings, including any equations and rearrangement of equations you use, and
the correct scientific units.
An ecological investigation of an area of European grassland found that the
amount of solar energy reaching the grassland was 1.85 × 106 kJ m−2 y−1. The
grasses of the area used 3.3 × 103 kJ m−2 y−1 in respiration and showed a net
primary productivity (NPP) of 2.07 × 104 kJ m−2 y−1.

4

(a) What is the gross primary productivity (GPP) for this area of grassland?
(b) Calculate the photosynthetic efficiency, i.e. the percentage of solar energy
reaching the vegetation that is converted to GPP.
(c) The biomass consumption of the three main groups of animals feeding on the
grassland is shown in Table 2. Use the information in the table to calculate
the total increase in biomass of all three primary consumers in this food
chain.
Table 2 Biomass consumption and loss of energy through faeces and
respiration.
Grass biomass
consumed/kJ m−2 y−1

Energy used in
respiration/kJ m−2 y−1

Energy lost as
faeces/kJ m−2 y−1

Field mice

105

26

64

Grasshoppers

440

109.5

264.8

60

16

32

Small birds

(d) 0.8 kJ m−2 y−1 is the total energy value of the grasshopper biomass that is
consumed by their major predator, spiders. If 60% of the energy consumed
by spiders is unassimilated and 15% of it is converted to biomass, calculate
the energy lost to respiration by spiders.
(e) Calculate the percentage of the total grasshopper biomass increase, as
calculated in (c) that is lost over a year by pathways other than spider
predation (e.g. death, other predators).
(f) Some important groups of organisms that should be included in this food web
have been omitted from this account. Name one of them and state its role in
the ecosystem. (One or two sentences)

Question 4
We suggest that you tackle this question after you have studied Book 5,
Chapters 8, 9, 10, 13 and 14.
The question carries 40% of the marks for this assignment. It will be marked
according to how well you demonstrate in your answer the following learning
outcomes:
Kn1

knowledge and understanding of the gene as a unit of inheritance, sex
linked characters, genetic variation and natural selection

Kn3

the role of science in the world around us and in everyday life

C2

apply knowledge and understanding of scientific concepts to address
familiar and unfamiliar problems and their contribution to informed
debate about topical issues

Ky1

use mathematical skills appropriate to the study of science at this level
(probability)

Ky3

communicate scientific topics clearly and concisely, using methods and
scientific language appropriate to your purpose and audience

5

A poultry farmer hopes to profit from the current craze for keeping egg laying
chickens as pets and wishes to increase his stock of interesting and unusual
breeds.
(a) The farmer crossed a pure-breeding white chicken with a pure-breeding black
chicken and found that 100% of their offspring (the F1 generation) were an
attractive blue colour. Hoping to get more of these blue chickens he crossed
several of the F1 offspring, but found that he had the following numbers of
chickens in the F2 generation:
„

Black, 28

„

White, 30

„

Blue, 60.

Assign symbols to the alleles controlling these colour characters and draw
genetic cross diagrams illustrating both crosses (details of crosses may be laid
out as in Book 5, Figure 8.10, using lines or, as in the alternate way shown in
Book 5, Figure 8.11, using squares). Explain why the mode of inheritance of
feather colour in this case means that the farmer will never be able to develop
pure-breeding blue chickens. Use the hints for tackling genetic problems in
Book 5, Box 8.1, p. 172, to help you with these questions. (We expect you
will be able to do this in up to 120 words, excluding diagrams.)
(b) In chickens, males have two Z sex chromosomes (ZZ) and females have one
Z and one W sex chromosome (ZW). The mechanism for inheritance of the
sex chromosomes is exactly the same as for X and Y sex chromosomes in
other species. In chickens the character of ‘barred’ or striped feathers is Z­
chromosome linked. The barred feather allele ZB is dominant to the non­
barred feather allele Zb. Write down the genotype that would result in a non­
barred male and a barred female and explain why these are the only
genotypes that could result in these phenotypes. (We expect you will be able
to do this in up to 100 words.)
(c) In a cross between the chickens in part (b), what are all of the possible
offspring in terms of sex and feather barring of the F1 offspring? Include a
genetic cross scheme showing how you reached your answer.
(d) Some combinations of alleles are actually lethal. In chickens an autosomal
allele called ‘creeper’ results in short legs when it is heterozygous, but chicks
homozygous for the allele die inside the egg. If the farmer crossed two
creeper heterozygotes what is the probability that an offspring that hatched
and survived would be a short-legged creeper? Assign symbols for the alleles
and draw a genetic cross scheme to demonstrate how you reached your
answer.
(e) Read the following edited extract from a news article, published in 2008,
which discusses a recent study of genetic diversity in commercial chickens
raised for the egg and meat industry, then write an account of no more than
750 words entitled ‘Genetic variation is important for both wild chickens and
captive commercially bred chickens’.
You should use examples and information from the extract and S104
materials. Your account should be written for a student of S104, so you may
use scientific terminology if its meaning is clear in the context in which it is
used. You are advised not to use material outside the provided extract or
S104 materials, but if you do use such material, you must cite and reference it
correctly as described in Question 1 of this TMA. It is not necessary to
reference the S104 materials or the extract.

6

In the introduction to your account you should include a brief explanation of
what is meant by genetic variation within a population. Then write your
account using the following list as a guide to the points you should discuss in
your answer.
Briefly outline the cellular processes that result in a huge range of genetic
variation in wild populations of a sexually reproducing species such as the
chicken.

„

What are the conditions that are necessary for natural selection to act on
genetic diversity in the wild to allow species to adapt?

„

Which of these conditions is not fulfilled during selective breeding of
chickens in captivity?

„

How does selective breeding in captivity result in a reduction in genetic
diversity?

„

What are some of the disadvantages of losing genetic diversity and how
could the problem be overcome?

„

Is it important to improve genetic diversity in commercial chicken
stocks?

„

Finally, conclude with a brief summary that relates to the content and title of
your account.
Note: Your account should be written as continuous prose (not bullet points) and
you should not use headings. Use correct sentence construction and paragraphs
linked coherently and logically together. Take care that you do not exceed the
word limit, and give the number of words you use at the end of your account.
Edited abstract: Commercial Poultry Lack Genetic Diversity
As concerns such as avian flu, animal welfare and consumer preferences
impact upon the poultry industry, the reduced genetic diversity of
commercial bird breeds increases their vulnerability and the industry’s
ability to adapt. Researchers have found that commercial birds are
missing more than half of the genetic diversity native to the species,
possibly leaving them vulnerable to new diseases and raising questions
about their long-term sustainability.
The research, led by Hans Cheng of the U.S. Department of Agriculture,
is the first study to investigate the genetic diversity of basically an entire
agricultural commodity. Historically, chicken producers selected birds
for breeding based on certain desirable traits. Size was important for
broilers, while egg production was critical for layers. Despite the fact that
hundreds of chicken breeds exist, today’s commercial broilers are
descended from about three lines of chickens, and poultry used in egg
production come from only one specialised line.
The research team included government, university and industrial
scientists who conducted the study using the recently sequenced chicken
genome. Obtaining DNA from commercial birds, they identified the
number of different alleles found throughout the genome. By comparing
the commercial breeds with native and non-commercial birds, they found
that commercial lines had lost up to 90 percent of alleles in some cases.
Poultry is the leading meat consumed in the United States and in most
other countries, with chicken meat production increasing by 436 percent
since 1970, so maintaining a healthy genetic reservoir in food-producing
animals is crucial in order to protect the nutritional demands of a growing

7

global society. Recent concerns over avian flu point to the need to ensure
that even rare traits, such as those associated with disease resistance are
not totally missing in commercial flocks. It’s also important to preserve
non-commercial breeds and wild birds for the purpose of safeguarding
genetic diversity and interbreeding additional species with commercial
lines might help protect the industry.