Co-ordination and response .2 Flashcards
Is core body temperature in humans maintained at around 37 °C?
True.
What is the optimum temperature for enzyme activity in the human body?
Core body temperature in humans is around 37 °C.
Do enzymes become denatured if core body temperature increases too much?
True.
What happens to enzymes at high temperatures?
High temperatures can result in denaturing of enzymes, changing the shape of the active site so it no longer fits with the substrate.
What happens to animal cells if blood water content is too high?
Water will move into cells by osmosis and cells may burst.
What happens to animal cells if blood water content is too low?
Water will move out of cells by osmosis and the cells will shrink.
Define the term stimulus.
A stimulus is a change in environmental conditions, e.g. a change in blood glucose levels.
What are receptor cells?
Receptor cells are cells that detect stimuli, e.g. cells in the eyes detect changes in light levels.
Do effectors detect environmental stimuli?
False.
Who detects changes (stimuli) and transmits this information?
Receptor cells detect changes (stimuli) and transmit this information to the coordination centre.
Define the term effector.
An effector is a muscle or gland that brings about a response to restore normal conditions in the body.
Does a coordinated response involve a stimulus, a receptor, and an effector?
True.
Define the term coordination centre.
A coordination centre, such as the brain or spinal cord, receives and processes information from receptors and initiates responses.
Which effector releases oestrogen as part of the menstrual cycle?
The effector that releases oestrogen is the ovaries.
Why do plants need to respond to stimuli such as light and gravity?
Plants need to respond to stimuli to maximise their growth.
Define the term tropism.
Tropisms are directional growth responses to stimuli, such as light and gravity, in plants.
What is a positive tropism?
A positive tropism occurs when a plant grows towards a stimulus, e.g. growing towards light.
What is a negative tropism?
A negative tropism occurs when a plant grows away from a stimulus, e.g. growing against gravity.
Does positive geotropism result in upward growth away from gravity?
False.
What does positive geotropism result in?
Positive geotropism results in downward growth that is towards gravity; this occurs in roots.
Define the term phototropism.
Phototropism is the directional growth of plants in response to light.
Define the term geotropism (or gravitropism).
Geotropism is the directional growth response of plants in relation to gravity.
Do shoots show a positive phototropic response and a negative geotropic response?
True.
Do roots show a negative phototropic response and a positive geotropic response?
True.
Is auxin often described as a plant hormone?
True.
What effect does auxin have on cells in the shoots of plants?
Auxin stimulates cell elongation in plant shoots.
What happens to auxin distribution when light shines on one side of a shoot?
Auxin produced in the tip accumulates on the shaded side, causing faster elongation on the shaded side.
How does auxin distribution in response to light lead to phototropism?
Auxin accumulation on the shaded side causes cells on that side to elongate faster, leading to bending towards the light.
What will happen to the growth of a plant shoot that received even light on all sides?
It will grow straight upwards due to even auxin distribution.
How would auxin be distributed if a plant was placed in a dark room?
Auxin would be evenly distributed, and the plant shoots would continue to grow straight upwards.
How does information travel through the nervous system?
Information is transmitted along neurones in the form of electrical impulses.
How is information transmitted by the endocrine system?
Information is transmitted when hormones are carried by the blood to target cells.
Are hormones used to control functions that require instant responses?
False.
