How do polar bears maintain homeostasis in freezing cold weather?
Polar bears have several adaptations that help them maintain homeostasis in freezing cold weather:
1. Thick Insulation: Polar bears have a thick layer of blubber, which can be up to 4.5 inches (11 cm) thick, providing excellent insulation. This layer helps to retain body heat and prevent it from escaping into the cold environment.
2. Dense Fur: Their fur is comprised of a dense undercoat and long outer guard hairs. The hollow guard hairs trap air, creating an additional layer of insulation. The fur also appears white, which helps them camouflage in their snowy habitat.
3. Counter-Current Heat Exchange: Polar bears have a specialized circulatory system that helps them to conserve heat. The arteries and veins in their extremities are closely situated, allowing warm blood flowing from the core to pass heat to cold blood flowing from the extremities. This mechanism minimizes heat loss to the cold air.
4. Reduced Surface Area: Polar bears have relatively compact bodies with short ears and tails, which help to minimize heat loss. Having a reduced surface area decreases the amount of heat lost through radiation into the environment.
5. Energy Conservation: During extreme cold weather or when resting, polar bears conserve energy by entering a state of lower activity or hibernation-like sleep called "walking hibernation." This enables them to reduce their metabolic rate and minimize energy expenditure while maintaining body temperature.
6. Behavioral Adaptations: Polar bears often curl up into a tight ball to minimize the exposed surface area when they rest. They also seek shelter from the wind and storms by digging snow dens or utilizing rocky outcrops.
By combining these adaptations, polar bears are able to withstand the freezing cold temperatures and maintain a relatively stable internal body temperature even in the harshest Arctic conditions.
How do polar bears maintain homeostasis in freezing cold weather? (1 point)
Responses
Their metabolism slows down to preserve heat.
Their metabolism slows down to preserve heat.
They hibernate in warm areas in order to heat their bodies.
They hibernate in warm areas in order to heat their bodies.
Their thick fur retains heat.
Their thick fur retains heat.
Their metabolism speeds up to produce heat.
Their thick fur retains heat.
Which example shows an organism that cannot reach homeostasis through internal changes? (1 point)
Responses
A dog shivers when it is too cold.
A dog shivers when it is too cold.
Circulation decreases in a bird when it becomes too warm.
Circulation decreases in a bird when it becomes too warm.
A person gets a fever in response to a flu infection.
A person gets a fever in response to a flu infection.
A lizard is cold, and it moves to a sunny rock to warm up.
A lizard is cold, and it moves to a sunny rock to warm up.
How is homeostasis achieved?(1 point)
Responses
Cells maintain internal stability.
Cells maintain internal stability.
Cells secrete stomach enzymes.
Cells secrete stomach enzymes.
Cells control involuntary movements.
Cells control involuntary movements.
Cells control voluntary movements.
Cells maintain internal stability.
How are muscle cells and bone cells similar?(1 point)
Responses
Both gather information from inside and outside the body.
Both gather information from inside and outside the body.
Both make it possible for you to respond to your environment by moving.
Both make it possible for you to respond to your environment by moving.
Both control involuntary movements such as the beating of your heart.
Both control involuntary movements such as the beating of your heart.
Both release sweat when the temperature gets too warm.
Both make it possible for you to respond to your environment by moving.
What is the function of an organ system? (1 point)
Responses
to be a basic unit of organization with bodies
to be a basic unit of organization with bodies
to work together to do a specific job
to work together to do a specific job
to control movement in internal organs
to control movement in internal organs
to organize a group of similar cells
to work together to do a specific job
Which is most complex?(1 point)
Responses
cells
cells
organ system
organ system
organs
organs
tissues
organ system
Which organ of the respiratory system is located inside the lungs?(1 point)
Responses
bronchioles
bronchioles
nasopharynx
nasopharynx
trachea
trachea
larynx
bronchioles
Which organ in the excretory system filters blood?(1 point)
Responses
kidney
kidney
bladder
bladder
ureter
ureter
urethra
kidney
What is the term for changes in the internal or external environment that cause a response?(1 point)
Responses
signals
signals
messages
messages
nerves
nerves
stimuli
stimuli
How do signals from sensory neurons reach motor neurons?(1 point)
Responses
Through interneurons in the brain and spinal cord that connect sensory neurons and motor neurons.
Through interneurons in the brain and spinal cord that connect sensory neurons and motor neurons.
Signals from sensory neurons do not get sent to motor neurons.
Signals from sensory neurons do not get sent to motor neurons.
Motor neurons signal for the body to move the signal toward them.
Motor neurons signal for the body to move the signal toward them.
Signals move from dendrite to dendrite towards motor neurons.