bio circulation

Question 1

Compare the structure and function of arteries, veins, and capillaries.

Answer 1

Arteries: Thick muscular walls to withstand high pressure; carry oxygenated blood away from the heart (except pulmonary artery).
Veins: Thinner walls with valves to prevent backflow; carry deoxygenated blood towards the heart (except pulmonary vein).
Capillaries: Very thin walls (one cell thick) to allow exchange of gases, nutrients, and waste between blood and tissues.

Question 2

Why are capillaries arranged in dense networks around tissues?

Answer 2

Dense networks increase the surface area for efficient diffusion of oxygen and nutrients into cells and removal of carbon dioxide and waste products.

Question 3

What are the two circuits in a double circulatory system, and why is this system more efficient?

Answer 3

Pulmonary circuit: Transports blood between the heart and lungs for oxygenation.
Systemic circuit: Delivers oxygenated blood to the body.
Efficiency: Keeps oxygenated and deoxygenated blood separate, maintaining high pressure in systemic circulation for better delivery of oxygen to tissues.

Question 4

How do muscles and valves help in blood circulation?

Answer 4

Muscles: Contract to squeeze blood through veins, especially in limbs, aiding venous return to the heart.
Valves: Prevent backflow of blood in veins, ensuring one-way movement towards the heart.

Question 5

Fish Single Circulatory System, Describe the disadvantages of a single circulatory system for a land animal.

Answer 5

Blood pressure is low after passing through the gills, which slows the delivery of oxygen and nutrients to tissues.
This is less efficient for high-energy activities needed by land animals, which require faster oxygen delivery for movement and maintaining body temperature.

Question 6

Why do veins have valves but arteries do not?

Answer 6

Veins transport blood under lower pressure and need valves to prevent backflow. Arteries are under high pressure, so backflow is not an issue.

Question 7

What feature of capillaries allows efficient diffusion of substances?

Answer 7

Their walls are only one cell thick, reducing the diffusion distance.

Question 8

How does the double circulatory system benefit mammals compared to a single system?

Answer 8

It allows higher blood pressure and more efficient oxygen delivery to tissues.

Question 9

Why might fish not need a double circulatory system?

Answer 9

Fish have lower energy demands and are supported by water, so slower oxygen delivery is sufficient for their needs.

Question 10

What structural features make capillaries suited for the exchange of substances?

Answer 10

Capillaries have walls that are one cell thick, allowing for short diffusion distances.
They have a large surface area due to their extensive network, enhancing exchange efficiency.
Narrow diameter ensures close proximity to cells for effective diffusion.

Question 11

Why is blood flow slow in capillaries, and how is this beneficial?

Answer 11

Blood flow is slow because capillaries are narrow and there are many of them, which increases resistance. This slow flow allows more time for the exchange of oxygen, carbon dioxide, nutrients, and waste between blood and tissues.

Question 12

How do capillaries facilitate gas exchange in the lungs?

Answer 12

Capillaries surround alveoli, where oxygen diffuses from the alveoli into the blood, and carbon dioxide diffuses from the blood into the alveoli. The thin walls and close contact enhance this process.

Question 13

Capillaries are described as “semi-permeable.” What does this mean, and why is it important?

Answer 13

Semi-permeable means capillary walls allow specific substances like oxygen, glucose, and waste products to pass through but prevent large molecules like proteins from leaking out. This maintains proper blood composition and supports efficient exchange.

Question 14

Why are capillary networks denser in active tissues like muscles?

Answer 14

Active tissues require more oxygen and nutrients for energy production and produce more waste products. Dense capillary networks ensure sufficient delivery and removal of these substances.

Question 15

Explain the role of osmosis in capillaries.

Answer 15

Osmosis in capillaries involves the movement of water into or out of the blood depending on the concentration gradient. For example:

Water moves out at the arterial end where blood pressure is high.
Water moves in at the venous end due to the osmotic pull of plasma proteins.

Question 16

What happens if capillaries are damaged, and why is it significant?

Answer 16

Damage to capillaries can lead to leakage of blood into tissues (bruising) and disruption of the exchange of substances, which may affect tissue health and function.

Question 17

How do capillaries interact with the lymphatic system?

Answer 17

Some fluid and small molecules that leak out of capillaries into tissues are collected by the lymphatic system. This system helps maintain fluid balance and prevents swelling (edema).

Question 18

what is lymphatic system

Answer 18

The lymphatic system is a crucial part of the immune system and circulatory system. It consists of a network of vessels, tissues, and organs that work together to transport lymph, a clear fluid containing white blood cells (lymphocytes), which help fight infection and maintain fluid balance in the body.

Question 19

Name three main components of the lymphatic system and describe their functions.

Answer 19

Lymph: A clear fluid that carries white blood cells and removes waste from tissues.
Lymphatic Vessels: Transport lymph throughout the body.
Lymph Nodes: Filter lymph and house immune cells to fight infections.

Question 20

What are two primary functions of the lymphatic system?

Answer 20

Maintains fluid balance by returning excess interstitial fluid to the bloodstream.
Supports the immune system by filtering pathogens and producing white blood cells.

Question 21

How do lymph nodes help the body fight infections?

Answer 21

Lymph nodes filter pathogens from the lymph and contain white blood cells that identify and attack these pathogens, helping to eliminate infections.

Question 22

What is the role of the lymphatic system in fat absorption?

Answer 22

Specialized lymphatic vessels called lacteals in the digestive system absorb fats and fat-soluble vitamins from the small intestine and transport them to the bloodstream.

Question 23

What condition occurs when the lymphatic system fails to properly drain fluid, and what are its symptoms?

Answer 23

The condition is called lymphedema, which leads to swelling (usually in the arms or legs) due to the build up of lymphatic fluid

Question 24

Define the term “resolution” in the context of microscopy.

Answer 24

Resolution is the ability of a microscope to distinguish between two points that are close together, providing greater clarity and detail in the image.

Question 24

What is the main difference between a light microscope and an electron microscope?

Answer 24

Light microscope: Uses light to magnify images, suitable for viewing live specimens and cells in general detail.
Electron microscope: Uses electrons, providing higher magnification and resolution, allowing the observation of subcellular structures.
2. Magnification Formula
Question: The image of a cell is 100 mm wide, and the actual cell is 0.02 mm wide. Calculate the magnification.
Answer:

Magnification = Image size ÷ Actual size
Magnification = 100 ÷ 0.02 = 5000x
3. Resolution
Question: Define the term “resolution” in the context of microscopy.
Answer: Resolution is the ability of a microscope to distinguish between two points that are close together, providing greater clarity and detail in the image.

4. Uses of Microscopes
   Question: Why are electron microscopes particularly useful for studying viruses?
   Answer: Viruses are extremely small and cannot be seen with a light microscope. The high magnification and resolution of electron microscopes allow scientists to study their detailed structure.
5. Preparing a Slide
   Question: Describe how to prepare a slide of an onion cell to observe it under a light microscope.
   Answer:

Peel a thin layer of onion epidermis.
Place it on a microscope slide.
Add a drop of iodine solution (stain) to make structures visible.
Carefully place a cover slip on top, avoiding air bubbles.
Observe under the microscope.
6. Converting Units
Question: Convert 2 mm into micrometers (µm).
Answer:

1 mm = 1000 µm
2 mm = 2 × 1000 = 2000 µm
7. Advancements in Microscopy
Question: How has the development of the electron microscope improved our understanding of cell biology?
Answer: Electron microscopes have allowed scientists to see detailed subcellular structures, such as ribosomes and mitochondria, leading to a better understanding of cell functions and processes like protein synthesis and respiration.

These questions cover the key areas related to microscopes in the AQA GCSE Biology syllabus, including practical skills, calculations, and theoretical knowledge.

Question 24

The image of a cell is 100 mm wide, and the actual cell is 0.02 mm wide. Calculate the magnification.

Answer 24

Magnification = Image size ÷ Actual size
Magnification = 100 ÷ 0.02 = 5000x

Question 25

Why are electron microscopes particularly useful for studying viruses?

Answer 25

Viruses are extremely small and cannot be seen with a light microscope. The high magnification and resolution of electron microscopes allow scientists to study their detailed structure.

Question 26

Describe how to prepare a slide of an onion cell to observe it under a light microscope.

Answer 26

Answer:

Peel a thin layer of onion epidermis.
Place it on a microscope slide.
Add a drop of iodine solution (stain) to make structures visible.
Carefully place a cover slip on top, avoiding air bubbles.
Observe under the microscope.

Question 27

How has the development of the electron microscope improved our understanding of cell biology?

Answer 27

Electron microscopes have allowed scientists to see detailed subcellular structures, such as ribosomes and mitochondria, leading to a better understanding of cell functions and processes like protein synthesis and respiration.

Question 28

difference between light microscope and electron microscope

Answer 28

A light microscope uses visible light for illumination, providing lower magnification (up to 1500x) and resolution (about 200 nm), suitable for viewing live specimens and general cellular structures. It produces colored images and requires simple preparation. In contrast, an electron microscope uses a beam of electrons, offering much higher magnification (up to 2,000,000x) and resolution (up to 0.2 nm), making it ideal for studying subcellular structures like organelles. However, it requires complex specimen preparation, works only with non-living specimens due to vacuum conditions, and produces black-and-white images. Light microscopes are more affordable and widely accessible, while electron microscopes are expensive and limited to advanced research.

Question 29

difference between coarse and fine objective knobs in a microscope

Answer 29

Coarse Focus Knob:

Makes large adjustments to the focus.
Moves the stage (or the lens) significantly, making it useful for finding the specimen initially.
Typically used with low-power objectives (e.g., 4x or 10x), as high-power objectives may require more precise adjustments.
Fine Focus Knob:

Makes small, precise adjustments to the focus.
Used to sharpen the image after the specimen is roughly focused.Essential for high-power objectives (e.g., 40x or 100x), where small changes can significantly affect the clarity of the image.
Together, these knobs help achieve clear and detailed views of specimens under the microscope.

Question 30

What is the primary difference between the coarse focus knob and the fine focus knob on a microscope?

Answer 30

The coarse focus knob makes large adjustments to the focus, useful for locating the specimen, while the fine focus knob makes small, precise adjustments to sharpen the image, especially when using high-power objectives.

Question 31

Why is the fine focus knob especially important when using high-power objectives on a microscope?

Answer 31

The fine focus knob allows for small, precise adjustments to achieve a clear and sharp image when using high-power objectives (e.g., 40x or 100x), as these objectives require fine-tuning for optimal clarity.

Question 32

Why should the coarse focus knob be used with low-power objectives and not with high-power objectives?

Answer 32

The coarse focus knob makes large adjustments to the focus, which could cause damage or misalignment with high-power objectives. It is best used with low-power objectives, where large movements can help locate the specimen without affecting the image quality.

Question 33

what moves the stage up

Answer 33

The coarse focus knob is typically used to move the stage up and down in large increments, helping to initially locate and focus on a specimen.