100% satisfaction guarantee Immediately available after payment Both online and in PDF No strings attached
logo-home
Previously searched by you
Previously searched by you
logo
CP1 write up - Investigate the effect of caffeine on heart rate in Daphnia £2.99
Add to cart
Quickly navigate to
Preview
  2.  
  3. PEARSON (PEARSON)
  4.  
  5. Biology 2008
  6.  
  7. Core Practicals

Exam (elaborations)

CP1 write up - Investigate the effect of caffeine on heart rate in Daphnia
 0 purchase

Edexcel A Biology A level core practical Write ups. All include an introduction, hypothesis, variables, method, results, evaluations... CP1 - Investigate the effect of caffeine on heart rate in Daphnia

Preview 2 out of 7  pages

Document information

  • July 23, 2024
  • 7
  • 2022/2023
  • Exam (elaborations)
  • Questions & answers

Subjects

Written for

All documents for this subject (12)

Seller

avatar-seller
maiaj

Content preview

Core Practical 1


Core practical 1 - investigating effect caffeine on heart rate in Daphnia

Aim: to investigate how varying the concentration of caffeine can affect the heart rate of
daphnia

Introduction:
The genus ‘daphnia’ are planktonic crustaceans which are commonly known as ‘water fleas’
and commonly found in freshwater. Its heart beats at around 200 times per minute at 20°C
and as it is a poikilothermic being, its temperature is dependent on its environmental
temperature. Therefore its heartbeat will get slower in cold water and increase in hot water.
(Tomar, n.d.).

Caffeine is a central nervous system stimulant found in the seeds, fruits, nuts, or leaves of a
number of plants native to Africa, East Asia and South America and is the most widely
consumed psychoactive drug. Caffeine works by leading to the blockading of adenosine
receptors and increasing autonomic nervous system (ANS) activity through the release of
plasma catecholamines, inducing tachycardia and increased blood pressure.

When adenosine binds to its receptors, neural activity slows down, and you feel sleepy.
However caffeine acts as an adenosine-receptor antagonist meaning that it binds to these
same receptors, but without reducing neural activity (Lazarus et al., 2011). This means that
adenosine cannot bind, preventing you from feeling sleepy. Therefore causing you to stay
alert and agitated.

Catecholamines are a group of hormones produced in the adrenal glands that are released
in response to emotional or physical stress as part of the fight or flight response. The main
types of catecholamines are epinephrine (adrenaline), norepinephrine (noradrenaline) and
dopamine. (www.medicalnewstoday.com, 2020). Catecholamines increase heart rate, blood
pressure, breathing rate, muscle strength, and mental alertness. They also reduce the
amount of blood going to the skin and increase blood flow to the major organs, such as the
brain, heart, and kidneys. Both of these responses cause the body to be more agitated and
speeds up heart rate.

Hypothesis : The heart rate of daphnia will increase as the concentration of the caffeine
increases as caffeine is a stimulant that triggers release of adrenaline and speeds up heart
rate.

Variables :
Independent variable : the concentration of caffeine given to the daphnia ranging from 0%
to 0.5%
Dependent variable : the heart rate of the daphnia in bpm

Control variables
- Use daphnia of similar size from the same stock and of the same age to ensure that
each daphnia used have a similar resting heart rate. Smaller and younger will have
faster heart rates than bigger and older ones.

, Core Practical 1


- Use the same equipment and the same method so that any variation in heart rates is
due to the caffeine solution and not any other factor such as differences in equipment
or method to record results.
- volume of solutions - use the same number of drops on daphnia each time so that
they are exposed to the same conditions and amount of caffeine and prevent any
unwanted variations in results.
- stress of daphnia - try minimise stress of daphnia (explained in ethical considerations
section)
- Time to acclimatise : leave daphnia in caffeine solution for the same amount of time
to acclimatise (eg 5 minutes) as the longer the daphnia is exposed, the longer the
caffeine has to diffuse into their system. They need to be exposed for the same
amount of time so they have roughly the same amount of caffeine in their system and
variations in results are caused by changes in the concentration alone.
- PH doesnt need to be controlled because it doesn't affect the daphnia
- Daphnia is poikilothermic meaning its metabolic rate is affected directly by the
temperature of the environment. Therefore the temperature of the environment
should be recorded and considered to give the heart rate at any given temperature.


Ethical Considerations
We use daphnia because
- Very common so no threat to species existence or dependent species (does not affect food web)
- No threat to their reproduction because they reproduce asexually → no lost genetic
variation
- Transparent so heart is visible
- Daphnia have a simple nervous system so dont not suffer physical or mental stress. However, there
are still debates over animal rights and due to lack of consent, we try to minimise the amount of
suffering.

To reduce suffering :
- Daphnia may be killed by chlorine in tap water. Any tap water used should be left to stand for 24 hours
first to let the chlorine dissipate
- May need too long to recover after the caffeine to use the same one for different concentrations in the
same practical
- After usage, place them in a ‘used’ daphne container and Dispose of Daphnia ethically, preferably by
returning them to a freshwater pond or stream (natural habitat)
- Store in conditions that replicate their natural habitat
- Working at good pace to minimise time daphnia are under stress
- Daphnia are poikilothermic (cold blooded). Turn off the microscope lamp when not viewing
the fleas → ethical
- Not using an excessive concentration of caffeine
- Use a lot of water and do not use a coverslip in order to maintain sufficient oxygen to the daphnia



Risk Assessment
- wear goggles to protect your eyes from any solutions or pond water getting in your eyes.
- Do not touch microscope or cables with wet hands as it uses electricity
- wash hands after handling daphnia and pond water to prevent any cuts from getting
infected by pond water or solutions

The benefits of buying summaries with Stuvia:

Guaranteed quality through customer reviews

Guaranteed quality through customer reviews

Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.

Quick and easy check-out

Quick and easy check-out

You can quickly pay through credit card for the summaries. There is no membership needed.

Focus on what matters

Focus on what matters

Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!

Frequently asked questions

What do I get when I buy this document?

You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.

Satisfaction guarantee: how does it work?

Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.

Who am I buying these notes from?

Stuvia is a marketplace, so you are not buying this document from us, but from seller maiaj. Stuvia facilitates payment to the seller.

Will I be stuck with a subscription?

No, you only buy these notes for £2.99. You're not tied to anything after your purchase.

Can Stuvia be trusted?

4.6 stars on Google & Trustpilot (+1000 reviews)

64257 documents were sold in the last 30 days

Founded in 2010, the go-to place to buy revision notes and other study material for 15 years now

Start selling

Recently viewed by you

Exam (elaborations) ·

(0)

SNHU HIS100 5-2 passed Quiz Historical Interpretations Southern New Hampshire University

Summary ·

(6)

Samenvatting deeltentamen 1: 'Why? Explaining the Holocaust'

Exam (elaborations) ·

(0)

AQA A-Level GEOGRAPHY Paper 1 Physical Geography MS 2021

Exam (elaborations) ·

(0)

Biotechnology |Synthetic Seeds Questions and Answers

Summary ·

(1)

Psychologie hoofdstuk 9

Summary ·

(0)

Samenvatting Humane evolutie cursusdeel 2

Other ·

(0)

Alevel English Literature Pearson Edexcel Paper 1 Drama Othello Shakespeare Critical Quotes Critics List Bank
£2.99
  • (0)
Add to cart
Added