U1T1
Which type of cell has membrane bound organelles?
Which type of macromolecule is broken down by amylase into simple sugars?
Carbohydrates
What is a thermoreceptor?
A type of sensory receptor responding to changes in temperature
How do adherence factors help pathogens cause disease in the human body?
They help pathogens stick to host cells or tissues, allowing them to colonise and resist being washed away, which is the first step in establishing infection
Despite being 95% water, this fruit can conduct electricity and has been used to power low-voltage devices in science fair experiments. What is the fruit?
Lemon
This organelle is responsible for producing energy (ATP) through cellular respiration.
Describe the active site
What part of an enzyme binds to the substrate to catalyse a reaction?
In the stimulus-response model, list the correct sequence of components involved in a negative feedback loop.
Stimulus → Receptor → Control Centre → Effector → Response
List the functions of the complement system.
Cell Lysis
Opsonisation
Enhance Inflammation
Chemotaxis
Neutralisation
Why does ice float in water?
Because its molecules form a crystalline structure that’s less dense than liquid water
Contrast totipotent and pluripotent stem cells.
Totipotent cells can become any cell type, including extra-embryonic tissues like the placenta.
Pluripotent cells can become any body cell, but not extra-embryonic tissues?
Describe one structural feature of the villi in the small intestine that increases efficiency of nutrient absorption.
They have a large surface area due to microvilli, which increases the rate of nutrient diffusion into the bloodstream
What is the function of the myelin sheath in a neuron, and how does it affect the transmission of nerve impulses?
It insulates the axon and allows faster transmission of the action potential by enabling saltatory conduction between the nodes of Ranvier
A patient shows a strong antibody response but does not develop symptoms after being exposed to a virus. Propose a reason why
Artificially acquired active immunity, likely from a vaccine that triggered antibody production without causing disease and signs/symptoms
The number of bacteria living in and on your body outnumber your human cells. Roughly how many bacterial cells are in your body?
39 trillion
How do the respiratory and circulatory systems work together to exchange gases in a multicellular organism?
The respiratory system brings in oxygen and removes carbon dioxide, while the circulatory system transports these gases between the lungs and the body’s cells
In an enzyme experiment, the reaction rate decreased after reaching 37°C, even though more substrate was added. Suggest a reason why.
The enzyme may have denatured due to high temperature, changing the shape of the active site so it can no longer bind to the substrate
Explain how ADH and the kidney work together to regulate water balance in the human body when a person is dehydrated, using the negative feedback model.
Dehydration increases blood osmolarity → Osmoreceptors detect the change → Hypothalamus signals the pituitary to release ADH → ADH increases water reabsorption in the kidney’s collecting ducts → Urine volume decreases → Water balance is restored
What are memory B and T cells?
These cells are formed during the first exposure to the pathogen and respond more quickly upon re-exposure by rapidly producing specific antibodies (B cells) and destroying infected cells (T cells), leading to faster clearance of the virus.
This animal has three hearts, blue blood, and can taste with its arms. What is it?
An octopus
In an experiment investigating the effect of surface area-to-volume ratio (SA:V) on diffusion, what result would you expect when comparing a small cube to a large cube, and why?
The small cube would have a faster rate of diffusion because it has a higher SA:V ratio, allowing substances to diffuse more efficiently across the membrane
During exercise, the oxygen concentration in muscle capillaries is higher than in muscle tissue. Based on this, in which direction will oxygen move, and why?
Oxygen will move from the capillaries into the muscle tissue by diffusion, because substances move from areas of higher to lower concentration
You are given data showing stomatal density (holes on plant) on the upper and lower leaf surfaces of three plant species. One species has very few stomata and a thick cuticle. What can you infer about this plant’s environment and how these structural features help maintain water balance?
The plant is likely adapted to a dry environment. Fewer stomata and a thick cuticle reduce water loss through transpiration, helping to conserve water as part of its homeostatic water balance
A disease outbreak begins with 50 cases. After vaccination of 70% of the population, new daily cases drop significantly. Using this data, what can you infer about the mode of transmission and the effectiveness of the strategy?
The disease likely spreads through person-to-person contact, and the vaccine is highly effective, as herd immunity was achieved by reducing the number of susceptible hosts
This planet rains liquid glass, has winds faster than 7,000 km/h, and would shred a spaceship in seconds.
Which horrifying exoplanet is this?
HD 189733b
(Bonus: it’s a real planet, 63 light years away, and very, very unpleasant.)