biology research
what are you going to study and why
heart is a crucial organ that circulates blood throughout the body, supplying nutrient and oxygen to
the cell while removing waste product. The heart rate, which is the number of times heart beats per
minutes can be influenced by various factors, including physical activity, stress and certain
substances. Particularly., it has been demonstrated that various substances such as caffeine, nicotine
and alcohol have different effect on heart rate. The reason why I am studying this subject is to have
an understanding of the effect of substances on the heart rate can be used to make an informed
medical treatment decision.
What is the topic of interested
The topic of interest is how does caffeine affect heart rate in daphnia
Daphnia, also referred ton as water fleas, are small aquatic crustaceans that have long served as a
model organism in toxicology and physiology research. Due to their transparent exoskeleton, which
makes it simple to observe their internal organs, which includes their hearts , these tiny creatures
are especially helpful for researching the effect of caffeine on the heart rate. daphnia can be
exposed to various substance, and researcher can monitor changes in the heart rate and use this
data to better understand how these substances can affect human and other larger organisms. This
makes daphnia the perfect model for researching how different substances affect heart rate and
identifying potential heath risk to human.
Questions about heart rate
Why is daphnia used in the experiment ?
Small crustaceans called daphnia—also called water fleas—live in freshwater habitats like ponds,
lakes, and streams. For fish and other aquatic organisms, they are a vital source of food. Daphnia are
great organisms to use in bioassays because they are cheap, easy, and sensitive to changes in water
chemistry. It is quick to grow a culture of test organisms because they reach maturity in just a few
days.
Daphnia can be used for bioassays that don't use death as the endpoint because they are
transparent. For instance, you can check their heart rate or see if they've eaten using a microscope.
Both of these symptoms are indicators of stress. You could decide to measure one of these other
endpoints if you are concerned that your experiments will kill Daphnia. However, it is important to
keep in mind that even in ideal circumstances, these organisms only live for a month or two, and in
the wild, the majority of them are eaten within the first few days or weeks of their existence.
Cornell.edu. (2009). Environmental Inquiry - Bioassays Using Daphnia. [online] Available at:
http://ei.cornell.edu/toxicology/bioassays/daphnia/ [Accessed 20 Mar. 2023].
,Due to the abundance of daphnia, also known as water fleas, neither the species itself nor the
dependent species (via food webs) are in any real danger of extinction. Daphnia reproduce asexually
as genetic clones, meaning there is no risk to genetic diversity, and they do not pose a threat to
sexual reproduction. Daphnia's nervous systems are less developed than those of humans, so they
are less sensitive to pain. In addition, since Daphnia are transparent, no dissection is required to see
the heart.
Isa, Dr. (2017). Effect of Caffeine on Daphnia Heart Rate. [online] Snab Biology. Available at:
https://snabbiology.co.uk/effect-of-caffeine-on-daphnia-heart-rate/ [Accessed 20 Mar. 2023].
Freshwater microcrustacean keystone species Daphnia is a model organism with a number of useful
advantages, including its small body size (2–5 mm), brief life cycle, ease of handling, high fecundity,
parthenogenetic reproduction, and low maintenance requirements. Under a microscope or pair of
binocular magnifying glasses, Daphnia's internal organs can be seen due to their translucent
chitinous exoskeleton. They serve as models for testing the effects of various'social drugs,' also
known as recreational drugs, like coffee, tobacco, and alcohol because they are highly sensitive
animals with fundamental biological responses that are remarkably similar to those of humans.
Miguel Faria, H. (2022). From drugs to climate change: hands-on experiments with Daphnia as a
model organism. [online] Science in School. Available at:
https://www.scienceinschool.org/article/2022/hands-on-experiments-daphnia/ [Accessed 20 Mar.
2023].
Why does caffeine increase heart rate in Daphnia?
Some of the effects of noradrenaline and adrenaline on the heart are mimicked by caffeine. Caffeine
also raises the level of cAMP in the sinoatrial node via a different mechanism that does not involve
beta-1 adrenoceptors. When cAMP levels rise, the sinoatrial node becomes more electrically active,
depolarizes, and begins to "beat" more quickly. The heart is also affected by caffeine. Similar to how
adrenaline and noradrenaline act on the heart's main pumping chambers (ventricles), it has the
potential to speed up the rate at which each heartbeat contracts and relaxes. This means that along
with beating more quickly, the heart's individual beats are also linked to a greater volume of blood
ejected into the circulation per unit time. This is referred to as raising cardiac output. Strong coffee
or tea, in quantities of two to three cups, contains enough caffeine (and a chemical with a similar
action known as theobromine) to raise heart rate in humans by 5 to 20 beats per minute.
Royal Society of Biology (2019). Investigating Factors Affecting the Heart Rate of Daphnia. [online]
practicalbiology.org. Available at: https://practicalbiology.org/control-and-communication/control-
of-heart-rate/investigating-factors-affecting-the-heart-rate-of-daphnia [Accessed 20 Mar. 2023].
As soon as you take your first sip of coffee, caffeine starts to stimulate your central nervous system
by entering your blood through your stomach and small intestine. The receptors in the cells within
your heart are stimulated by the caffeine and increases your heart rate. Your blood flow also
increases as your heartbeat quickens by about three beats per minute. Caffeine's ability to raise your
heart rate can start working in as little as 15 minutes and last for about six hours.
AdventHealth (2021). How Does Caffeine Affect Your Heart? [online] AdventHealth. Available at:
https://www.adventhealth.com/blog/how-does-caffeine-affect-your-heart [Accessed 20 Mar. 2023].
, The hearts of daphnia magna are reputed to be similar to those of humans. Daphnia are accustomed
To determine a similar effect to what would occur in the human heart, test the impact of various
substances on the heart rate of laboratory animals. We predicted that giving the Daphnia caffeine
would raise their heart rate. Whereas the Daphnia's heart rate would drop with the addition of
ethanol. The investigation that Consisted of five trials for each answer. According to our data,
caffeine significantly increased their Heart rate (p=0.005024), and that ethanol significantly slowed
the Daphnia's heart rate (p=0.028729). The outcomes can be used to determine how ethanol and
caffeine would impact people.
Kurien, B., Perkins, C., Tullos, C., Mittermeier, Q. and Hjalmarson, E. (2018). The Effect of Caffeine
and Ethanol on the BPM of Daphnia magna. [online] Available at:
https://undergradsciencejournals.okstate.edu/index.php/JUBLI/article/viewFile/8785/1910
[Accessed 20 Mar. 2023].
Numerous organisms' heart rates can be raised by caffeine. The heart rate increases as a result of
caffeine's binding to receptors on the surface of heart muscle cells, which raises the level of cAMP
inside the cells. Overall, this has the effect of accelerating glycolysis and raising the amount of ATP
available for muscle contraction and relaxation. Additionally, theophylline, a byproduct of the
metabolism of caffeine, acts as a chronotrope and inotrope, raising heart rate and productivity.
UKEssays. November 2018. The effect of caffeine on heart rate. [online]. Available from:
https://www.ukessays.com/essays/biology/the-effect-of-caffeine-on-heart-rate-biology-essay.php?
vref=1 [Accessed 20 March 2023].
What is the independent variable in the Daphnia experiment?
The independent variable was the concentration of caffeine we administrated to the daphnia
Brann, T. (2017). Investigating factors affecting the heart rate of Daphnia. [online] A Level Revision.
Available at: https://tbrann.weebly.com/biology-blog/investigating-factors-affecting-the-heart-rate-
of-daphnia [Accessed 20 Mar. 2023].
The seven caffeinated solutions that are tested on the Daphnia magna are considered the
independent variables.
gzipwtf.com. (2019). What is the independent variable in the Daphnia heart rate experiment? –
Gzipwtf.com. [online] Available at: https://gzipwtf.com/what-is-the-independent-variable-in-the-
daphnia-heart-rate-experiment/ [Accessed 20 Mar. 2023].
Why does heart rate increase when temperature increases Daphnia?
Daphnia is a poikilothermic species, which means that the temperature of its environment and
its body directly affect the metabolic rate. The rate (cardiac frequency) at which the heart beats
changes in response to the change in metabolic rate.
gzipwtf.com. (2019). What is the independent variable in the Daphnia heart rate experiment? –
Gzipwtf.com. [online] Available at: https://gzipwtf.com/what-is-the-independent-variable-in-the-
daphnia-heart-rate-experiment/ [Accessed 20 Mar. 2023].
what are you going to study and why
heart is a crucial organ that circulates blood throughout the body, supplying nutrient and oxygen to
the cell while removing waste product. The heart rate, which is the number of times heart beats per
minutes can be influenced by various factors, including physical activity, stress and certain
substances. Particularly., it has been demonstrated that various substances such as caffeine, nicotine
and alcohol have different effect on heart rate. The reason why I am studying this subject is to have
an understanding of the effect of substances on the heart rate can be used to make an informed
medical treatment decision.
What is the topic of interested
The topic of interest is how does caffeine affect heart rate in daphnia
Daphnia, also referred ton as water fleas, are small aquatic crustaceans that have long served as a
model organism in toxicology and physiology research. Due to their transparent exoskeleton, which
makes it simple to observe their internal organs, which includes their hearts , these tiny creatures
are especially helpful for researching the effect of caffeine on the heart rate. daphnia can be
exposed to various substance, and researcher can monitor changes in the heart rate and use this
data to better understand how these substances can affect human and other larger organisms. This
makes daphnia the perfect model for researching how different substances affect heart rate and
identifying potential heath risk to human.
Questions about heart rate
Why is daphnia used in the experiment ?
Small crustaceans called daphnia—also called water fleas—live in freshwater habitats like ponds,
lakes, and streams. For fish and other aquatic organisms, they are a vital source of food. Daphnia are
great organisms to use in bioassays because they are cheap, easy, and sensitive to changes in water
chemistry. It is quick to grow a culture of test organisms because they reach maturity in just a few
days.
Daphnia can be used for bioassays that don't use death as the endpoint because they are
transparent. For instance, you can check their heart rate or see if they've eaten using a microscope.
Both of these symptoms are indicators of stress. You could decide to measure one of these other
endpoints if you are concerned that your experiments will kill Daphnia. However, it is important to
keep in mind that even in ideal circumstances, these organisms only live for a month or two, and in
the wild, the majority of them are eaten within the first few days or weeks of their existence.
Cornell.edu. (2009). Environmental Inquiry - Bioassays Using Daphnia. [online] Available at:
http://ei.cornell.edu/toxicology/bioassays/daphnia/ [Accessed 20 Mar. 2023].
,Due to the abundance of daphnia, also known as water fleas, neither the species itself nor the
dependent species (via food webs) are in any real danger of extinction. Daphnia reproduce asexually
as genetic clones, meaning there is no risk to genetic diversity, and they do not pose a threat to
sexual reproduction. Daphnia's nervous systems are less developed than those of humans, so they
are less sensitive to pain. In addition, since Daphnia are transparent, no dissection is required to see
the heart.
Isa, Dr. (2017). Effect of Caffeine on Daphnia Heart Rate. [online] Snab Biology. Available at:
https://snabbiology.co.uk/effect-of-caffeine-on-daphnia-heart-rate/ [Accessed 20 Mar. 2023].
Freshwater microcrustacean keystone species Daphnia is a model organism with a number of useful
advantages, including its small body size (2–5 mm), brief life cycle, ease of handling, high fecundity,
parthenogenetic reproduction, and low maintenance requirements. Under a microscope or pair of
binocular magnifying glasses, Daphnia's internal organs can be seen due to their translucent
chitinous exoskeleton. They serve as models for testing the effects of various'social drugs,' also
known as recreational drugs, like coffee, tobacco, and alcohol because they are highly sensitive
animals with fundamental biological responses that are remarkably similar to those of humans.
Miguel Faria, H. (2022). From drugs to climate change: hands-on experiments with Daphnia as a
model organism. [online] Science in School. Available at:
https://www.scienceinschool.org/article/2022/hands-on-experiments-daphnia/ [Accessed 20 Mar.
2023].
Why does caffeine increase heart rate in Daphnia?
Some of the effects of noradrenaline and adrenaline on the heart are mimicked by caffeine. Caffeine
also raises the level of cAMP in the sinoatrial node via a different mechanism that does not involve
beta-1 adrenoceptors. When cAMP levels rise, the sinoatrial node becomes more electrically active,
depolarizes, and begins to "beat" more quickly. The heart is also affected by caffeine. Similar to how
adrenaline and noradrenaline act on the heart's main pumping chambers (ventricles), it has the
potential to speed up the rate at which each heartbeat contracts and relaxes. This means that along
with beating more quickly, the heart's individual beats are also linked to a greater volume of blood
ejected into the circulation per unit time. This is referred to as raising cardiac output. Strong coffee
or tea, in quantities of two to three cups, contains enough caffeine (and a chemical with a similar
action known as theobromine) to raise heart rate in humans by 5 to 20 beats per minute.
Royal Society of Biology (2019). Investigating Factors Affecting the Heart Rate of Daphnia. [online]
practicalbiology.org. Available at: https://practicalbiology.org/control-and-communication/control-
of-heart-rate/investigating-factors-affecting-the-heart-rate-of-daphnia [Accessed 20 Mar. 2023].
As soon as you take your first sip of coffee, caffeine starts to stimulate your central nervous system
by entering your blood through your stomach and small intestine. The receptors in the cells within
your heart are stimulated by the caffeine and increases your heart rate. Your blood flow also
increases as your heartbeat quickens by about three beats per minute. Caffeine's ability to raise your
heart rate can start working in as little as 15 minutes and last for about six hours.
AdventHealth (2021). How Does Caffeine Affect Your Heart? [online] AdventHealth. Available at:
https://www.adventhealth.com/blog/how-does-caffeine-affect-your-heart [Accessed 20 Mar. 2023].
, The hearts of daphnia magna are reputed to be similar to those of humans. Daphnia are accustomed
To determine a similar effect to what would occur in the human heart, test the impact of various
substances on the heart rate of laboratory animals. We predicted that giving the Daphnia caffeine
would raise their heart rate. Whereas the Daphnia's heart rate would drop with the addition of
ethanol. The investigation that Consisted of five trials for each answer. According to our data,
caffeine significantly increased their Heart rate (p=0.005024), and that ethanol significantly slowed
the Daphnia's heart rate (p=0.028729). The outcomes can be used to determine how ethanol and
caffeine would impact people.
Kurien, B., Perkins, C., Tullos, C., Mittermeier, Q. and Hjalmarson, E. (2018). The Effect of Caffeine
and Ethanol on the BPM of Daphnia magna. [online] Available at:
https://undergradsciencejournals.okstate.edu/index.php/JUBLI/article/viewFile/8785/1910
[Accessed 20 Mar. 2023].
Numerous organisms' heart rates can be raised by caffeine. The heart rate increases as a result of
caffeine's binding to receptors on the surface of heart muscle cells, which raises the level of cAMP
inside the cells. Overall, this has the effect of accelerating glycolysis and raising the amount of ATP
available for muscle contraction and relaxation. Additionally, theophylline, a byproduct of the
metabolism of caffeine, acts as a chronotrope and inotrope, raising heart rate and productivity.
UKEssays. November 2018. The effect of caffeine on heart rate. [online]. Available from:
https://www.ukessays.com/essays/biology/the-effect-of-caffeine-on-heart-rate-biology-essay.php?
vref=1 [Accessed 20 March 2023].
What is the independent variable in the Daphnia experiment?
The independent variable was the concentration of caffeine we administrated to the daphnia
Brann, T. (2017). Investigating factors affecting the heart rate of Daphnia. [online] A Level Revision.
Available at: https://tbrann.weebly.com/biology-blog/investigating-factors-affecting-the-heart-rate-
of-daphnia [Accessed 20 Mar. 2023].
The seven caffeinated solutions that are tested on the Daphnia magna are considered the
independent variables.
gzipwtf.com. (2019). What is the independent variable in the Daphnia heart rate experiment? –
Gzipwtf.com. [online] Available at: https://gzipwtf.com/what-is-the-independent-variable-in-the-
daphnia-heart-rate-experiment/ [Accessed 20 Mar. 2023].
Why does heart rate increase when temperature increases Daphnia?
Daphnia is a poikilothermic species, which means that the temperature of its environment and
its body directly affect the metabolic rate. The rate (cardiac frequency) at which the heart beats
changes in response to the change in metabolic rate.
gzipwtf.com. (2019). What is the independent variable in the Daphnia heart rate experiment? –
Gzipwtf.com. [online] Available at: https://gzipwtf.com/what-is-the-independent-variable-in-the-
daphnia-heart-rate-experiment/ [Accessed 20 Mar. 2023].
