20 Questions
What is the purpose of using a cover slip when preparing a wet mount?
To prevent air bubbles and to cover the specimen
What is the advantage of using Daphnia in the CPAC investigation?
Daphnia are transparent, allowing the observation of their internal organs, including their heartbeat.
What is the purpose of using a controlled variable in the CPAC investigation?
To keep certain factors constant, such as temperature and time, to ensure a fair test.
Why is it important to use a range of caffeine concentrations in the CPAC investigation?
To show a positive correlation between caffeine concentration and heart rate.
What is the reason for waiting 5 minutes after adding the caffeine solution to the Daphnia?
To allow the Daphnia to assimilate the caffeine.
Why is it considered unethical to cause distress or suffering to any living organism in scientific experiments?
Because it is immoral to subject living beings to harm or pain without their consent.
Why do some people believe it is more acceptable to perform experiments on invertebrates than vertebrates?
Because invertebrates are considered simpler organisms with a less sophisticated nervous system, which may imply they feel less pain.
What is the purpose of handling animals gently and keeping examination periods short?
To minimize potential harm and stress to the animals.
Why is it important to avoid extreme ranges of variables being tested in scientific experiments?
To prevent unnecessary harm or stress to the animals or organisms being tested.
What is the benefit of using a light microscope to observe the Daphnia in the CPAC investigation?
To observe the internal organs and heartbeat of the Daphnia.
What is the primary function of the circulatory system in multicellular organisms?
To carry raw materials from specialized exchange organs to body cells and remove metabolic waste.
What is the dipole nature of water molecules, and how does it contribute to their solubility?
The dipole nature of water molecules refers to their partial positive and negative charges, allowing them to dissolve ionic substances.
How do the structures of arteries and veins differ, and what are their adaptations for function?
Arteries have thick walls with elastic tissues to withstand high pressure, while veins have thinner walls and valves to prevent backflow. Arteries carry oxygenated blood away from the heart, and veins carry deoxygenated blood back to the heart.
What is the purpose of the cardiac cycle, and what is the sequence of events involved?
The cardiac cycle is an ongoing sequence of contraction and relaxation of the atria and ventricles to maintain blood circulation. The sequence involves atrial systole, ventricular systole, and cardiac diastole.
How do the structures of the atria and ventricles differ, and what are their functions?
The atria have thinner walls and receive blood, while the ventricles have thicker walls and pump blood out of the heart. The atria function as receiving chambers, and the ventricles function as pumping chambers.
What is the role of the atrioventricular valves and semilunar valves in the heart, and how do they function?
The atrioventricular valves prevent backflow of blood from ventricles into atria, and the semilunar valves prevent backflow of blood from aorta and pulmonary artery into ventricles.
What is the significance of the blood pressure and volume changes during the cardiac cycle?
Changes in blood pressure and volume enable the heart to pump blood efficiently and maintain circulation throughout the body.
How does the heart rate affect the cardiac cycle, and what are the implications of changes in heart rate?
The heart rate determines the frequency of the cardiac cycle, with changes in heart rate affecting blood circulation and oxygen delivery to tissues.
What is the relationship between the structure of capillaries and their function in gas exchange?
The thin walls and one-cell thick structure of capillaries enable rapid diffusion of oxygen and carbon dioxide, facilitating efficient gas exchange.
How does the water's high specific heat capacity contribute to the regulation of body temperature?
Water's high specific heat capacity allows it to absorb and release heat energy slowly, helping to maintain a stable body temperature.
Study Notes
Need for Circulatory System (1.1)
- Cells need energy, which is obtained through aerobic respiration using glucose and oxygen
- In single-celled organisms, materials can diffuse directly into the cell across the cell membrane due to short diffusion distances
- In multicellular organisms, mass transport systems are needed to carry raw materials from exchange organs to body cells and remove metabolic waste
- In mammals, the circulatory system, including the heart, is used to pump blood around the body, supplying nutrients and oxygen to individual cells and removing metabolic waste
Importance of Water in Transport (1.2)
- Water is vital to living organisms, making up 80% of a cell's content
- Water's functions:
- Solvent: allows substances to dissolve in it
- Transporting substances: makes it easier to transport substances
- Structure of water molecules:
- One oxygen atom and two hydrogen atoms joined by shared electrons (covalent bond)
- Oxygen atom has a slight negative charge, while hydrogen atoms have a slight positive charge, making water a dipolar molecule
- Hydrogen bonds form between water molecules due to their polar nature, which are weak and constantly breaking and reforming, allowing water to flow past each other in a liquid state
- Water's cohesive properties make it good for transporting substances
- Water is a good solvent, especially for ionic substances, due to its polar nature
- Water's high specific heat capacity helps maintain a stable environment
- Water's high surface tension is useful for some organisms, such as pond skaters
- Water is incompressible due to the lack of empty space between particles
- Water's density is highest at 4°C, with less dense ice floating on top of liquid water
Blood Vessels: Structure and Function (1.3)
- Arteries:
- Carry blood away from the heart to the rest of the body
- Carry oxygenated blood (except for the pulmonary artery)
- Have thick walls, narrow lumen, and smooth endothelium to maintain high pressure
- Arterioles:
- Branches of arteries that transport blood into capillaries
- Veins:
- Carry blood back to the heart
- Carry deoxygenated blood (except for the pulmonary vein)
- Have thin walls, large lumen, and valves to prevent backflow
- Capillaries:
- Smallest blood vessels where metabolic exchange occurs
- Carry both oxygenated and deoxygenated blood
- Have thin walls, small lumen, and pores for diffusion
Mammalian Heart: Structure and Function (1.4)
- Heart function:
- Pumps blood throughout the body
- Regulates blood pressure
- Heart structure:
- Left ventricle: thicker walls, pumps blood to the entire body
- Right ventricle: thinner walls, pumps blood to the lungs
- Atrioventricular valves: prevent backflow of blood from ventricles to atria
- Semi-lunar valves: prevent backflow of blood from aorta and pulmonary artery into ventricles
- Cardiac cycle:
- Atrial systole: atria contract, pushing blood into ventricles
- Ventricular systole: ventricles contract, pumping blood out of the heart
- Diastole: heart relaxes, allowing blood to flow back into the atria
- Heart rate regulation:
- Cardiac cycle: repeated sequence of contraction and relaxation
- Heart rate: number of heartbeats per minute
Investigating Heart Rate (1.4)
- Preparing a microscopic slide:
- Place specimen on slide
- Add a stain (optional)
- Cover with a coverslip
- Using a light microscope:
- Clip slide onto stage
- Select lowest-powered objective lens
- Adjust focus using coarse and fine adjustment knobs
- Investigating the effect of caffeine on heart rate of Daphnia:
- Use a controlled experiment with different concentrations of caffeine
- Measure heart rate of Daphnia using a microscope
- Plot a graph to show the effect of caffeine concentration on heart rate
Ethical Issues (1.17)
- Ethical concerns when experimenting on animals:
- Animals cannot give consent
- Animals may be subjected to painful procedures
- Invertebrates are often considered acceptable for experimentation due to their simpler nervous system
- Ethical considerations when experimenting on invertebrates:
- Minimize harm and distress to the animals
- Handle animals gently and with care
- Keep examination periods short
- Avoid extreme ranges of variables, such as extreme temperatures
- Return animals to their holding tank promptly
Learn about the importance of circulatory system in living organisms, including the need for mass transport systems in multicellular organisms and the limitations of diffusion.
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