Untitled Flashcards Set

"Define a stimulus in the context of organisms." "A stimulus is a change in an organism's internal or external environment."

"Explain the importance of responding to stimuli for organisms." "Responding to stimuli increases an organism's chance of survival."

"Describe what a tropism is." "A tropism is the growth of a plant in response to a directional stimulus."

"Differentiate between positive and negative tropism." "Positive tropism is growth towards a stimulus, while negative tropism is growth away from a stimulus."

"Summarize the role of growth factors in flowering plants." "Specific growth factors, such as auxins, move from growing regions to other tissues to regulate growth in response to directional stimuli."

"How does indoleacetic acid (IAA) affect cell elongation in shoots and roots?" "In shoots, high concentrations of IAA stimulate cell elongation, while in roots, high concentrations inhibit cell elongation."

"Explain the process of gravitropism in flowering plants." "Gravitropism involves IAA production in the tip of the shoot/root, diffusion down the shoot/root, increased concentration on the lower side, stimulating elongation in shoots and inhibiting it in roots, causing shoots to bend away from gravity and roots to bend towards it."

"What is the role of auxins in plant growth?" "Auxins are hormone-like growth substances that regulate growth in response to directional stimuli."

"Describe how IAA concentration affects root and shoot growth differently." "High IAA concentration stimulates cell elongation in shoots but inhibits it in roots."

"How do plants respond to gravity through gravitropism?" "Plants respond to gravity by bending shoots away from gravity and roots towards gravity due to the differential effects of IAA."

"Explain phototropism in flowering plants." "Phototropism involves the production of IAA in the tip of the shoot or root, which then diffuses down. IAA accumulates on the shaded side, stimulating cell elongation in shoots and inhibiting it in roots, causing shoots to bend towards light and roots to bend away."

"Describe the role of taxes in maintaining a mobile organism in a favorable environment." "Taxes are directional responses where an organism moves towards or away from a directional stimulus, helping it to navigate its environment effectively."

"What is kinesis and how does it differ from taxes?" "Kinesis is a non-directional response where the speed of movement or rate of direction change varies in response to a non-directional stimulus, unlike taxes which is directional."

"Provide an example of taxis in organisms." "An example of taxis is woodlice moving away from light to avoid predators."

"How do woodlice exhibit kinesis in response to their environment?" "Woodlice move faster in drier environments to increase their chances of finding areas with higher humidity, preventing dehydration."

"Explain the protective effect of a simple reflex involving three neurones." "A simple reflex is rapid due to only three neurones and few synapses, operates autonomously without involving conscious brain regions, and protects from harmful stimuli, such as escaping predators or preventing tissue damage."

"Identify a common mistake regarding the production of IAA in roots." "A common mistake is stating 'The root tip contains IAA.' The correct statement is that the root tip produces IAA."

"Clarify the misconception about growth on one side of the shoot or root." "The misconception is stating 'There is more growth on"

"Describe the myogenic nature of cardiac muscle." "Cardiac muscle is myogenic, meaning it can contract and relax without receiving electrical impulses from nerves."

"Identify the role of the sinoatrial node (SAN) in heart function." "The sinoatrial node (SAN) acts as the pacemaker of the heart, sending regular waves of electrical activity across the atria, causing them to contract simultaneously."

"Explain the function of non-conducting tissue in the heart." "Non-conducting tissue between the atria and ventricles prevents the electrical impulse from passing directly to the ventricles, which prevents immediate contraction of the ventricles."

"What happens at the atrioventricular node (AVN) during heart stimulation?" "The atrioventricular node (AVN) receives the wave of electrical activity and delays the impulse, allowing the atria to fully contract and empty before the ventricles contract."

"Describe the pathway of electrical activity from the AVN to the ventricles." "The AVN sends the wave of electrical activity down the bundle of His, which conducts the wave between the ventricles to the apex, where it branches into Purkyne tissue."

"How do the ventricles contract in response to electrical activity?" "The ventricles contract simultaneously from the base up due to the wave of electrical activity traveling through the Purkyne tissue."

"Label the key components involved in the heart's electrical conduction system." "Key components include the sinoatrial node (SAN), atrioventricular node (AVN), Bundle of His, and Purkyne tissue."

"Describe the location of chemoreceptors and pressure receptors in the body." "Chemoreceptors and pressure receptors are located in the aorta and carotid arteries."

"Define the role of baroreceptors in heart rate regulation." "Baroreceptors detect changes in blood pressure."

"How do chemoreceptors contribute to heart rate control?" "Chemoreceptors detect changes in blood CO2 concentration and blood pH."

"Explain the pathway of impulses from receptors to the heart." "Impulses are sent from baroreceptors and chemoreceptors to the medulla, which then sends impulses to the SAN along sympathetic or parasympathetic neurones."

"What effect does the sympathetic nervous system have on heart rate?" "The sympathetic nervous system increases heart rate by sending more frequent impulses to the SAN."

"What is the role of the parasympathetic nervous system in heart rate regulation?" "The parasympathetic nervous system decreases heart rate by sending less frequent impulses to the SAN."

"Describe the relationship between SAN impulses and heart rate." "More frequent impulses from the SAN lead to an increased heart rate, while less frequent impulses lead to a decreased heart rate."

"How does the medulla oblongata influence heart rate?" "The medulla oblongata controls heart rate via the autonomic nervous system, sending impulses that either increase or decrease heart rate."

"What common mistake is made when discussing the autonomic nervous system's role in heart rate?" "A common mistake is referring to the autonomic nervous system without specifying the sympathetic or parasympathetic pathways."

"Explain the impact of increased frequency of impulses on cardiac muscle contraction." "Increased frequency of impulses leads to more frequent contractions of cardiac muscle, resulting in an increased heart rate."

"What happens to heart rate when impulses are sent along parasympathetic neurones?" "Heart rate decreases when more frequent impulses are sent along parasympathetic neurones."

"Describe the adaptations of animals that need to conserve water." "Animals needing to conserve water have long loops of Henle, which create a thick medulla. This allows for more Na+ to be moved out, maintaining a Na+ gradient for longer, which helps maintain a water potential gradient for longer, enabling more water to be reabsorbed from the collecting duct by osmosis."

"How does water reabsorption occur in the distal convoluted tubule and collecting ducts?" "Water moves out of the distal convoluted tubule and collecting duct by osmosis down a water potential gradient, and this process is controlled by antidiuretic hormone (ADH), which increases their permeability."

"Define osmoregulation." "Osmoregulation is the control of water potential of the blood through negative feedback mechanisms."

"Describe the function of the hypothalamus in osmoregulation." "The hypothalamus contains osmoreceptors that detect changes in blood water potential. It produces more ADH when water potential is low and less ADH when water potential is high."

"What role does the posterior pituitary gland play in osmoregulation?" "The posterior pituitary gland secretes more or less ADH into the blood based on signals received from the hypothalamus."

"Explain the role of antidiuretic hormone (ADH) in osmoregulation." "ADH attaches to receptors on the collecting duct and distal convoluted tubule, stimulating the addition of aquaporins into cell-surface membranes, which increases the permeability of these cells to water, enhancing water reabsorption back into the blood and resulting in decreased urine volume and increased urine concentration."

"How does the body respond to a decrease in water potential of the blood?" "The body responds to a decrease in water potential by increasing the secretion of ADH, which enhances water reabsorption in the kidneys, leading to a decrease in urine volume and an increase in urine concentration."

"What happens when there is an increase in water potential of the blood?" "The body responds by decreasing the secretion of ADH, which reduces water reabsorption in the kidneys, leading to an increase in urine volume and a decrease in urine concentration."