YR11 - Topic Test 2 - Adaptations, Homeostasis

Question 1

Define Adaptation

Answer 1

Any heritable trait that helps an organism, such as a plant or animal, survive and reproduce in its environment

Question 2

Examples of Physical/Structural Adaptations

Answer 2

Beaks of a bird
Skin/Fur (Camoflague)
Big ears to cool down
Thick fur to keep warm
Small ear to reduce heat loss
Big eyes to see in the dark

Question 3

Definition and examples of structural adaptations

Answer 3

Physical features of an organism like the bill on a bird or the fur on a bear etc.

Question 4

Definition and examples of behavioural adaptations

Answer 4

Things organisms do to survive. The actions they do. For example, bird calls and migration

Question 5

Definition and examples of physiological adaptations

Answer 5

Internal systematic responses to external stimuli in order to help an organism maintain homeostasis (normal).
Some examples include temperature regulation, the release of toxins or poisons, releasing antifreeze proteins to avoid freezing in cold environments. camouflage etc.

Question 6

Nervous and Endocrine system differences

Answer 6

Nervous System:

• Electrical impulses are the messengers in the nervous system
• Brain and the spinal cord are involved in the nervous system
• Nerve impulses are transmitted through neurons

Endocrine System:

• Hormones are the chemical messengers in the endocrine system that target cells through the bloodstream
• Glands and organs like thyroid, pituitary glands and reproductive organs (ovaries and testes) are involved in the endocrine system.
• Hormones are transmitted through blood vessels.

Question 7

Define Homeostasis

Answer 7

Homeostasis is the ability to maintain a relatively stable internal state that persists despite changes in the world outside

Question 8

Purpose of Homeostasis

Answer 8

To maintain a normal balance within the body regarding its temperature, salt concentration, water concentration, and food intake.

Question 9

Thermoregulation Stimulus-Response Model

Answer 9

TOO HOT
Stimulus: too hot
Receptor: thermoreceptors
Control Center: Hypothalamus
Effector: Sweat glands, Diaphragm, Muscles around blood vessels dilate (piloerection)
Response: Sweat, Breathing, Vasodilation (to increase blood flow to extremities).

TOO COLD
Stimulus: too cold
Receptor: thermoreceptor
Control Centre: Hypothalamus
Effector: skeletal muscles, hair follicles go rigid, muscles around blood vessels (piloerection)
Response: shivering to increase heat, goosebumps, vasoconstriction (decrease blood flow)

Question 10

Blood Glucose Regulation Stimulus-Response Model

Answer 10

HGL
Stimulus: high glucose in the blood (from food)
Receptor: pancreas, beta cells
Signal: Insulin - the hormone that travels to send a message
Effector: liver, muscles, adipose tissue (take up glucose and store in their cells as glycogen
Response: to reduce blood glucose by taking it into cells

LGL:
Stimulus: fasting blood glucose is too low
Receptor: pancreas, alpha cells
Effector: liver, muscles and adipose tissue
Response: release glucose from glycogen

Both Negative Feedback

Question 11

Osmoregulation (Water/Salt Balance) Stimulus-Response Model

Answer 11

INCREASE IN WATER/SALT
Stimulus: Increase of water (e.g. drinking water)
Receptors: Baroreceptors and Osmoreceptors
Control Center: Pituitary Gland —> Hypothalamus
Effector: Kidney
Response: Water released —> Peeing

DECREASE IN WATER/SALT
Stimulus: A drop in the level of water
Receptors: Baroreceptors and Osmoreceptors
Control Center: Pituitary Gland —> Hypothalamus
Effector: Kidney
Response: Reabsorb water in kidney, urine is more concentrated

Both of these are negative feedback models as the result is they return back to the body’s normal state (homeostasis).

Question 12

Define Endothermic

Answer 12

any process which requires or absorbs energy from its surroundings, usually in the form of heat

Can produce it’s own body heat

Question 13

Define Ectothermic and examples

Answer 13

Any animal whose regulation of body temperature depends on external sources, such as sunlight or a heated rock surface. The ectotherms include the fishes, amphibians, reptiles, and invertebrates.

They can’t produce their own heat

Question 14

Define Negative Feedback

Answer 14

A reaction that causes a decrease in function. It occurs in response to some kind of stimulus.

Question 15

Define Positive Feedback

Answer 15

Opposite of negative feedback
It encourages a physiological process or amplifies the action of a system. Positive feedback is a cyclic process that can continue to amplify your body’s response to a stimulus until a negative feedback response takes over

Question 16

Define Hormones

Answer 16

A hormone is any member of a class of signalling molecules, produced by glands in multicellular organisms, that are transported by the circulatory system to target distant organs to regulate physiology and behaviour

Question 17

Define Osmoregulation

Answer 17

Osmoregulation is the process of maintaining salt and water balance across membranes within the body.

Question 18

Define Thermoregulation

Answer 18

The ability of an organism to keep its body temperature within certain boundaries, even when the surrounding temperature is very different.

Question 19

How do plants adapt to their environment

Answer 19

They will often move towards the sunlight and will often adapt according to the season. E.g. Winter, Summer. Some plants move every day. They turn their leaves toward the Sun. Sunflower plants turn toward the Sun. They do this to catch as much sunlight as possible.

Question 20

Desert Plant Adaptation

Answer 20

Desert plants have plenty of sunlight. But they receive very little water. When it does rain, they soak up as much water as they can. Their roots are often very close to the surface of the soil or sand. They are ready and waiting to catch any drop of water that falls.
Their next challenge is to hang onto the water. Desert plants have a thick, waxy surface. They have spikes instead of leaves. This stops a lot of water from being lost across their outside surface.

Question 21

Rainforest Plant Adaptation

Answer 21

Rainforests are found in hot, rainy regions of the world. They have a lot of sunlight and a lot of rain. Thousands of plant species grow here. They all compete for light and minerals. Rainforest trees grow very fast and extremely tall. Some stand over 150 feet (46 meters). The tallest trees get the most sunlight. In this way, they compete with each other for survival.

Question 22

How do humans regulate water balance?

Answer 22

Through the kidneys. The kidneys can adjust the concentration of the urine to reflect the body’s water needs, conserving water if the body is dehydrated or making urine more dilute to expel excess water when necessary. ADH is a hormone that helps the body to retain water by increasing water reabsorption by the kidneys.

Question 23

What is the body’s response to low water levels?

Answer 23

When the body is low in water, the pituitary gland secretes vasopressin or ADH into the bloodstream. Vasopressin/ADH stimulates the kidneys to conserve water and excrete less urine.

Question 24

Reasonable range of BGL (blood glucose levels)

Answer 24

between 4.0–7.8mmol/L.

Question 25

what organs are involved in regulating blood glucose levels

Answer 25

Pancreas and liver

Question 26

How do organisms respond to changes in their environment?

Answer 26

As a group – adaptations

Individual – regulation (internal) in changes to their (external)

Question 27

What organ is involved in regulating temperature in the body?

Answer 27

Hypothalamus

Question 28

What organs are involved in regulating water balance in the body?

Answer 28

Kidney

The signal is sent to brain

Question 29

Major hormones

Answer 29

ADH, Insulin and Glucagon

Question 30

What is ADH

Answer 30

ADH is also called arginine vasopressin. It’s a hormone made by the hypothalamus in the brain and stored in the pituitary gland. It tells your kidneys how much water to conserve. ADH constantly regulates and balances the amount of water in your blood.

Question 31

What is insulin

Answer 31

Insulin helps control blood glucose levels by signalling the liver and muscle and fat cells to take in glucose from the blood. Insulin, therefore, helps cells to take in glucose to be used for energy. If the body has sufficient energy, insulin signals the liver to take up glucose and store it as glycogen.

Question 32

Glucagon function

Answer 32

Glucagon’s role in the body is to prevent blood glucose levels dropping too low. To do this, it acts on the liver in several ways: It stimulates the conversion of stored glycogen (stored in the liver) to glucose, which can be released into the bloodstream.