Mohammed Salam Unit 6: LA:A
Pondweed
Introduction:
In this report, I will discuss about the pondweed where there are many limiting factors that affect
photosynthesis in pondweed. I've chosen altering light intensity as my chosen abiotic factor, my
desired aim of investigation is the rate of oxygen production in pondweed I chose this because I
want to see how it actually affects the pondweed production of oxygen when altering the light
intensity. Photosynthesis is essential to all plants like pondweed the photosynthesis occurs when the
plants take in carbon dioxide and water from the surrounding air. Inside the pondweed there are
chlorophyll which absorbs sunlight to produce oxygen and glucose the formula for photosynthesis
equation is (Carbon dioxide + water= glucose + oxygen) 6CO 2 + 6H2O = C6H12O6 + 6O2 the oxygen that
are produced from the photosynthesis are just by-products which benefits to all life forms on earth.
When pondweed produce oxygen, it forms bubbles in the water and released into the surroundings
in the water.
A journal article was introduced in 2018 called ‘Elodea Canadensis (Canadian pondweed)’ shows
good understanding about the pondweed. Elodea Canadensis (pondweed) is found in slower flowing
rivers. The pondweed originates from North America, St Lawrence valley, Pacific West Coast and the
great lakes regions are the place where this pondweed comes from. In the mid – 1800s the plant was
introduced in the UK; the pondweed is now found globally due to mass reproduction. The middle
and upper leaves are about 2 to 5 mm wide the leaves from the upper whorls grow closely together.
In pondweed some of them features flowers which states that they are male flowers. These grow
from the stem where petals grow 5 mm and sepals grow in between 3.5 - 5.0 mm long. Female
flowers are also grown in some pondweed, but the petals and sepals are shorter than males, female
flowers have stalks that are about 15 cm long and the petals are white. (Duenas-Lopez, M.A., Popay,
I. and Dawson, H., 2018)
Critical evaluation:
This source was produced in 2018 which is to be 4 years old but then it was later updated in 2022
which is recent this shows that the authors are constantly checking and making modifications to
ensure that the source can be accurate enough. There are three authors in this article Manuel Angel
Duenas – Lopez, Ian Popay and Hugh Dawson. Ian Popay is a Landcare Research in New Zealand; his
works are very well known and has produced many sources in his life. There is no evidence behind
Ian’s educational purposes as they are not published online, so this could mean that the information
from the source may not be valid or reliable. M.A Duenas – Lopez is from the University of Córdoba
in Spain which could prove that his work may be reliable and valid but there is also no evidence for
Hugh’s qualifications also and also M.A Duenas – Lopez this also states that these authors lack
experience when producing articles on the website so again this source may not be valid. The three
authors have accomplished of their work making it to be as a relevant source where it generally
discusses the specific information about elodea Canadensis like it matches the journal article title
and explains in detail about the pondweed, this also makes the source to be reliable. This source is
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,Mohammed Salam Unit 6: LA:A
also relevant to the experiment because it discuses about the pondweed, which makes the source to
be suitable for use of evidence in method.
In 2013 a journal article was published called ‘Improving photosynthesis’ this journal article provides
good explanation about photosynthesis. The photosynthesis is very important to most life forms on
earth the photosynthesis is a process which occurs on plants where the plants can capture sunlight
and convert it into biochemical energy which is glucose. Plant growth also depends on
photosynthesis without the aid of photosynthesis oxygen will not be produced and therefore most
life forms from earth will not exist. The process from the photosynthesis initially commences when
the light from the sun is absorbed by the plant organelles, chlorophyll is responsible for absorption
of the light the sun light allows it to produce O 2 (oxygen) in plants. In the process of photosynthesis,
plants take in the CO2 (carbon dioxide) and H2O (water) from air and soil. Carbon assimilation is
introduced when the CO2 are absorbed in the plants to produced glucose. The photosynthesis
equation is (carbon dioxide + water = glucose + oxygen) 6CO 2 + 6H2O = C6H12O6 + 6O2 at the end, the
oxygen and glucose are the by-products. (Evans, J.R. 2013).
Critical evaluations:
This source was produced in 2013 which is to be 9 years old there was no recent updates or
modifications on the author’s work which suggests that the scientific context may be outdated and
may not be reliable and could also affect the accuracy of the author’s work since new breakthroughs
in science are always introduced and could show better scientific explanation. The source was
obtained from a company website called plant physiology® where most scientific journal articles are
published. Plant physiology® is a very reliable website where anyone can access it for free the
website is used commonly for journal article producers. The author’s work was obtained from the
company website it will encourage the other users that it is a reliable source. John Richard Evans is
the producer of this journal source he is a professor of Plant Science Division, Research School of
Biology in Australian National university. It is stated that John is well known journal article producer
with estimates of at least 20 different sources are produced, this shows that he has the experience
of creating scientific source making his works to be more reliable. John gained his PhD of plant
physiology in 1984, this makes his source to be more reliable and accurate but however, since he
gained his PhD in 1984 it may affect the reliability and accuracy of his work because new syllabus is
generally introduced and replaces the old syllabus and thus it may mean that his work is not valid.
His work is relevant to this specific topic which he titled in his work like it’s about photosynthesis and
clearly explains about the process of the photosynthesis. His works are relevant to the pondweed
experiment and the hypothesis because it discusses about how photosynthesis work, this creates
link to the investigation and the chosen method.
In 2022 a website called ‘Plantlife.org.uk’ have proposed a source called ‘Canadian Pondweed’ which
discuss about the pondweed and its issue in the environment the pondweed is considered to be an
invasive plant where it tends to spread very quickly and harmfully. The pondweed grows very fast
and it’s a problem to the environment, it harms the fish and the invertebrate. The pondweed is an
aquatic plant, and they form as dense when this occurs it can reduce the biodiversity of waterways,
where there will be rise and falls in the oxygen present in the water which as a result low amount
oxygen can make the fish and invertebrate suffocate. In England and Wales, it is an offensive to grow
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, Mohammed Salam Unit 6: LA:A
or plant this type of pondweed in the wild due to the damages that can be caused to the
environment. (Plantlife, 2022).
Critical evaluation:
This source was obtained from a company website called Plantlife. The source appears to be
produced in 2022 which was recently made and shows that they have the most recent information
about the pondweed it shows that since it was made recently it may give valid information about the
pondweed. However, this source has no name for the producer of this article which could state that
the person who is making this source is unclear that the author may lack on experience when
producing scientific information, it states that the source could be unreliable. Plantlife is a company
website that contains information on different types of plants, but their main goal is that they try to
help the environment. The relevance of this source clearly matches to the title of the work since it is
titled as ‘Canadian pondweed’ and it discusses about the pondweed. This source is also relevant to
the investigation of oxygen production in pondweed because it talks about the pondweed and could
be used as evidence to support both chosen method and the hypothesis.
An article called ‘Photosynthesis Formula: Types, Components and Process’ was introduced in 2021
where it explains about the photosynthesis. Photosynthesis is a process where plants, algae and
some microorganisms can convert light energy into a chemical energy. All organisms on Earth
survive by photosynthesis, a cycle that is fundamental to the process. If photosynthesis never
existed, then it would be impossible to have the existence of life on earth because photosynthesis is
responsible for producing food. In plants, bacteria, and algae they have a pigment which are
responsible for capturing the sunlight. A green pigment is called chlorophyll which is the most
important one where it can capture red light and blue light. The photosynthesis happens in the
chloroplasts. Regions in grana and stroma are where the photosynthesis takes place. The grana are
disc – shaped and have like plates stacked up in columns and these are composed of membranes.
The thylakoids are in the individual discs which have the responsibility of transferring the electrons.
There are two stages of photosynthesis process. The first stage is called light – dependent stage.
Chloroplast thylakoids are involved in these reactions, which require sunlight. The breakdown of a
water molecule into H+ and OH- begins when a photon strikes chlorophyll A and activates the
reaction centre. The hydrogen atom and the oxygen atom make up each water molecule. During
photolysis of water molecules, oxygen (O 2) is formed by pairing of oxygen atoms. As ATP is formed
by adding a third phosphate to ADP, H+ ions provide energy to an enzyme called ATP synthase. In
this reaction, NADP+ and hydrogen ions bond together to form the energy-carrying molecule
NADPH. (Rout, S., 2021)
Critical evaluation:
Sushmita Rout is the producer of this source she is an Academic teacher at Embibe. Embibe is a
company website that produces resources for students who are preparing to revise for exam, it is for
anyone from schools, private tutors, and government institutes. Sushmita is currently working at
Embibe full – time since she is an academic teacher at Embibe her source would be reliable. This
source appears to be produced from 2021 which was made recently and means that her resource is
reliable. It was then modified from 2022 which was done recently, she modified the resource which
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