Survival and response Flashcards
Q1: What is a stimulus?
A: A detectable change in the internal or external environment that produces a response.
Q2: Define taxis.
A: A directional response to a stimulus
Q3: What is kinesis?
A: A non-directional response where the speed of movement or turning increases in unfavorable conditions.
Q4: What is a reflex arc?
A: The pathway of information in a reflex action: stimulus → receptor → sensory neuron → relay neuron → motor neuron → effector.
Q5: What is the role of the autonomic nervous system?
A: Controls involuntary actions including heart rate and digestion.
Q6: A plant grows toward light. Name and explain the type of response.
A: Phototropism: a directional growth response where auxins accumulate on the shaded side causing cell elongation and bending toward the light.
Q7: Explain the advantage of positive gravitropism in roots.
A: Roots grow downward into the soil to access water and minerals and anchor the plant.
Q8: Why do woodlice show kinesis in dry environments?
A: To increase movement and the likelihood of finding a favorable moist environment reducing water loss.
Q9: A graph shows the response time for a reflex in different conditions. Suggest why response time is faster when a harmful stimulus is applied.
A: Harmful stimuli trigger faster responses due to direct pathways involving fewer synapses in the reflex arc.
Q10: Data shows auxin concentration at different points on a shoot. Explain why the shaded side has more auxin.
A: Auxin redistributes to the shaded side of the shoot promoting cell elongation and bending toward light.
Q11: Describe how coordination occurs in a simple reflex action.
A: Stimulus → receptor detects it → sensory neurons transmit impulses to the spinal cord → relay neurons connect to motor neurons → motor neurons carry impulses to effectors → response.
Q12: Explain how IAA controls plant growth.
A: In shoots high IAA concentration promotes cell elongation. In roots
Q13: Which part of the nervous system controls reflex actions?
A: The central nervous system (CNS).
Q14: In which direction do auxins move in a plant?
A: Auxins move to the shaded or lower side in response to light and gravity.
Q15: Compare and contrast taxis and kinesis.
A: Taxis is a directional response to a stimulus while kinesis is a non-directional response where movement rate depends on stimulus intensity.
Q16: Explain the role of synapses in coordinating responses.
A: Synapses ensure one-way transmission of impulses and allow integration and filtering of signals.
Q17: A shoot grows horizontally. Explain why its tip bends upward.
A: Gravity causes IAA to accumulate on the lower side promoting cell elongation there
Q18: Why does severing a spinal cord disrupt reflex actions?
A: Reflex arcs rely on uninterrupted pathways within the spinal cord to transmit impulses.
Q19: Describe the importance of reflex actions in animals.
A: Reflex actions are fast automatic responses that protect organisms from harm
Q20: Explain why tropisms are beneficial for plant survival.
A: Tropisms ensure plants grow toward light (for photosynthesis) and roots grow into the soil (for stability and nutrient absorption).
Q21: How would you design an experiment to investigate phototropism in seedlings?
A: Place seedlings in boxes with light entering from one side. Measure the angle of growth toward the light source. Use a control group with uniform light.
Q22: Explain how you could use a choice chamber to investigate woodlice response to humidity.
A: Place woodlice in a chamber with dry and moist sections. Record their distribution over time. Conclude based on movement patterns.
Q23: Explain why gravitropism is an advantage for seed germination.
A: Ensures roots grow downward into soil for water and minerals while shoots grow upward for light.
Q24: A mutation prevents IAA redistribution in plants. Predict the effect on growth.
A: Plants would not exhibit directional growth responses like phototropism or gravitropism affecting their survival.
Q25: Discuss the role of coordination in survival linking reflex actions to long-term responses like tropisms.
A: Reflex actions provide immediate protection from harm
