Science 2024 Flashcards
What are some examples of multicellular organisms?
Examples of Multicellular organisms include Humans, animals and plants.
Multicellular organisms have evolved sophisticated mechanisms to respond to changes in their environment. Examples include:
Nervous system responses: Animals use their nervous systems to quickly detect and respond to stimuli like pain, heat, or pressure. For instance, when touching something hot, reflex actions enable the body to pull away almost instantly.
Hormonal regulation: In response to stress, the endocrine system releases hormones such as adrenaline in animals, triggering a fight-or-flight response, which increases heart rate and energy availability.
Immune system activation: When pathogens are detected, the immune system responds by deploying white blood cells to attack and destroy invaders, ensuring the organism’s protection.
What are some examples of other examples of specific reactions in the environment? (Cold, dark rooms, dehydration in plants)
Cold temperatures: When exposed to cold, humans get goosebumps, a reflex inherited from ancestors with thicker body hair. Goosebumps raise the hairs to trap heat, although this is less effective in modern humans.
Dark rooms: In low light, human pupils dilate (enlarge) to allow more light into the eyes, improving vision in the dark.
Dehydration in plants: When water is scarce, plants close their stomata (tiny pores on leaves) to reduce water loss through transpiration.
What makes up the nervous system?
The nervous system is divided into two sections, the central nervous system (CNS) and the peripheral nervous system (PNS). The central nervous system is composed of the brain and the spinal cord whereas the peripheral nervous system consists of all the nerves that connect to the central nervous system.
What is the role of the nervous system?
The Nervous System’s role is to coordinate and control your body’s actions. It detects stimuli through receptor cells, which send messages along nerves to the central nervous system (CNS) for processing. The CNS, composed of the brain and spinal cord, sends signals through the peripheral nervous system (PNS) to muscles or glands to trigger a response. Sensory neurons carry signals to the CNS, interneurons process them, and motor neurons send signals to effectors like muscles. For example, if you touch something hot, your nervous system quickly signals your muscles to move your hand away.
What is the role of the endocrine system?
The endocrine system is a chemical coordination system that controls body functions by releasing hormones. These hormones are tiny amounts of chemicals produced by glands and are transported through the bloodstream to specific target organs. Once they reach their target, hormones trigger a response, helping regulate processes like growth, metabolism, and mood. For example, insulin is a hormone released by the pancreas to control blood sugar levels.
Compare (similarities and differences) the nervous and endocrine system
The nervous and endocrine systems both regulate body functions and target specific organs, helping the body communicate with its internal and external environments to coordinate responses. Additionally, both systems work together through communication links for efficient regulation. However, they operate differently. The nervous system uses fast electrical impulses through neurons, allowing for quick and short-lived responses, and can be under voluntary or involuntary control. In contrast, the endocrine system is slower, relying on hormones sent through the bloodstream, with longer-lasting effects, and is always involuntary. They also contain different parts of the body, the nervous system is composed of the brain, spinal cord and nerves, whereas glands that make hormones such as the thyroid and pituitary are key in the endocrine system.
Outline the physical barriers to prevent the entry of pathogens
Skin is a physical barrier that prevents the entry of pathogens into the body. This is why when the
the skin is broken when cut and grazed the surrounding area will likely become infected.
The mucous membranes provide a barrier against foreign particles, capture them in its sticky mucus
and clear them out. Immune cells and natural antibodies in the mucus defend against pathogens
Cilia (hairs) that line the bronchus in the lungs move microbes and debris up and out of the airway.
Further, scattered through the cilia are goblet cells that secrete mucus which acts as a barrier
and traps pathogens.
Microflora acts as a physical barrier by occupying space and preventing pathogens from
establishing themselves. They also produce substances such as lactic acid, which inhibits
pathogen growth. For example, microflora can be found in the gut, where they help maintain a
balanced environment and prevent harmful bacteria from proliferating
Outline the chemical barriers to prevent the entry of pathogens
Tears contain a substance called Iysozyme, which has an antibacterial action and works to
prevent invasion and infection by microbes.
Stomach acid is a chemical barrier against infection. Its high Ph kills any pathogens. that have
been caught in mucus. in the airways or consumed in food or water.
Saliva acts as a barrier for pathogens by washing them away from the oral cavity and
throat, reducing the likelihood of infection. It also contains antimicrobial substances, such as
plasma B cells and antibodies, which eliminate harmful microorganisms.
Urine continuously flushes out bacteria and pathogens from the body. Additionally, resident cells
lining the urinary tract help reduce the presence and growth of pathogens. The acidity of urine
also creates an environment that is inhabitable for many pathogens.
Explain the inflammatory response
The inflammatory response is the biological process of the body defending itself against injury or
infection. It starts when immune cells release chemicals like histamines and cytokines after recognising
damage or pathogens. This increases blood flow and therefore blood vessels expand, causing redness
and warmth. This results in the vessels transporting the blood becoming more permeable, allowing
immune cells and proteins to enter the area, which creates swelling. White blood cells can now move in to
destroy the pathogens and anti-inflammatory signals help return the tissue to normal.
How do antibodies fight pathogens?
Antibodies are specialized proteins produced by the immune system in response to pathogens, such as
bacteria and viruses. They have a Y-shaped structure that allows them to bind specifically to these
pathogens. Once bound, antibodies work to eliminate the pathogens in several ways. First, they
neutralize the pathogen by limiting its ability to infect healthy cells. Next, antibodies opsonize,
coating pathogens to make them more recognizable to immune cells. Additionally, they can activate
the complement system, which helps destroy many pathogens. Finally, antibodies clump pathogens
together, making it easier for immune cells to target and eliminate multiple pathogens at once, allowing
for a faster and more efficient recovery.
Outline how vaccinations prevent infectious diseases:
Vaccines prevent infectious diseases by training the immune system to recognise and respond to
pathogens without causing illness. Vaccines usually introduce harmless parts of a pathogen into the
body, such as weakened or dead viruses. Once administered, the vaccine enters the
bloodstream, where the immune system recognizes these components as foreign. This triggers an
immune response, where white blood cells produce antibodies and activate other immune cells to
target the introduced material. The body also creates memory cells, which “remember” the pathogen.
If the person is exposed to the real pathogen later, their immune system quickly recognizes it and
Fights against it like previously done. This process provides long-term protection against diseases
like measles, polio, and smallpox.
Use examples to show how the interaction between the endocrine and nervous systems maintain humans as functioning organisms.
The nervous and endocrine systems interact to maintain humans as functioning organisms, especially during stressful situations or infections. For example, when the body senses danger or stress, the nervous system sends signals to the adrenal glands (part of the endocrine system) to release adrenaline. This hormone prepares the body for a “fight or flight” response by increasing heart rate, blood pressure, and energy availability. Another example is during an infection. The nervous system detects the infection and signals the endocrine system to release cortisol, a hormone that helps manage inflammation and supports the immune system in fighting off the pathogen. This cooperation ensures that the body’s response to infection is strong enough to fight the invader but controlled enough to avoid damaging healthy tissues. Through these interactions, the nervous and endocrine systems work together to maintain homeostasis, ensuring humans can function efficiently during stress, illness, or environmental changes.
Outline the three lines of defence in response to pathogens
Defence line 1: Physical and chemical barriers trying to prevent the entry of pathogens into the body
Defence line 2: General response to pathogens once they have entered the body. For example, fever, inflammation and phagocytes (white blood cells) that destroy anything foreign.
Defence line 3: Specific response to pathogens once they have entered the body. For example, T cells kill the pathogen-infected cells and B cells produce antibodies.
What is conduction and provide an example
Conduction is the transfer of heat through direct contact between materials, where heat moves from the hotter object to the cooler one. For example, when a metal spoon is placed in a hot pot, heat is conducted from the pot to the spoon.
What is convection and provide an example
Convection is the transfer of heat in liquids or gases through the movement of warmer, less dense regions rising and cooler, denser regions sinking. An example is the circulation of air in the atmosphere, where warm air rises and cool air descends.
Describe the particle level of solids
Particles are closely packed in a fixed arrangement and vibrate in place. They have strong forces of attraction and little movement, giving solids a definite shape and volume.
Describe the particle model of liquids
Particles are close together but can move past each other, allowing liquids to flow and take the shape of their container. They have weaker forces of attraction than solids, giving liquids a definite volume but no fixed shape.
Describe the particle model of gases
Particles are far apart and move freely in all directions with high energy. There are very weak forces of attraction, allowing gases to spread out and fill the volume of their container.
In a wave, what is the wavelength?
The distance between consecutive corresponding points of the same phase on the wave, such as two adjacent crests or troughs. Measured in meters (m).
What is the frequency?
The number of wave cycles that pass a point in one second. It is measured in hertz (Hz).
What is the Amplitude
The maximum displacement of a wave from its resting position. In a transverse wave, it is the height from the middle line to a crest or trough.
What is the speed?
The rate at which the wave travels through a medium. It is calculated as the product of wavelength and frequency and is measured in meters per second (m/s).
What is the crest?
The highest point of a transverse wave, where the wave reaches its maximum positive displacement.
What is the Trough?
The lowest point of a transverse wave, where the wave reaches its maximum negative displacement.
What is rarefaction?
The region in a longitudinal wave where particles are spread apart, creating low pressure. This occurs between compressions.
What is compression?
The region in a longitudinal wave where particles are closest together, creating high pressure.
What is the medium?
The substance through which a wave travels (e.g., air, water, or solids). The medium affects the speed and behaviour of the wave. Waves can be mechanical (require a medium) or electromagnetic (can travel through a vacuum).
What is the difference between longitudinal and transverse waves?
➡ Transverse waves cause the medium to move perpendicular to the direction of the wave. They look like hills.
➡ Longitudinal waves cause the medium to move parallel to the direction of the wave. They look like a barcode.
When calculating wave problems, what does the formula triangle look like? ie What is at the top and what is on the left and right?
Top = Speed m/s
Left = frequency Hz
Right = Wave length λ
Given a diagram, how would you determine which wave has the greatest wavelength?
Look at the distance between two consecutive crests (or troughs) on a transverse wave, or between two compressions (or rarefactions) in a longitudinal wave. The wave with the greatest distance between these points has the greatest wavelength.
