5.1.1 (Communication, Homeostasis and energy)

Question 1

What are the 4 conditions cells need to be maintained?

Answer 1

• suitable pH
• suitable temperature
• an (aq) environment
• freedom from toxins and excess inhibitors

Question 2

Why is communication essential for the survival of organisms?

Answer 2

Communication is essential for the survival of organisms because all living organisms must be able to detect and respond to changes in their internal and external environments.

Question 3

What triggers the necessary changes for survival in multicellular organisms?

Answer 3

In multicellular organisms, the changes necessary for survival are triggered by the nervous and endocrine systems.

Question 4

What are the two main forms of cell signaling?

Answer 4

The two main forms of cell signaling are neuronal signaling, which involves electrical signals carried by neurons, and chemical signaling, which involves the use of hormones.

Question 5

How does neuronal cell signaling differ from chemical signaling?

Answer 5

Neuronal cell signaling is faster and short term, whereas chemical signaling is slower and long term.

Question 6

What is endocrine signaling and how does it function?

Answer 6

Endocrine signaling involves the release of signaling molecules into the circulatory system for long-distance communication between cells.

Question 7

What is paracrine signaling and where does it occur?

Answer 7

Paracrine signaling occurs between cells that are in close proximity to each other, either directly or with the help of extracellular fluid.

Question 8

Describe autocrine signaling and its function.

Answer 8

Autocrine signaling is a form of signaling where a cell releases signals to stimulate its own receptors, triggering a response within itself.

Question 9

What is the purpose of homeostasis?

Answer 9

To ensure that a constant internal environment consisting of factors such as temperature, water potential, pH, and blood glucose level is maintained, despite changes in the external environment of the organism.

Question 10

What is the role of negative feedback in achieving homeostasis?

Answer 10

Negative feedback counteracts changes in internal conditions, restoring optimum conditions by reversing any deviations.

Question 11

What are the essential components for the negative feedback pathway to function?

Answer 11

sensory receptors (e.g., temperature receptors) to detect internal changes, and effectors (e.g., muscles, glands) to provide a response.

Question 12

How does the negative feedback pathway respond to changes in internal conditions?

Answer 12

When a change is detected, sensory receptors send signals via the nervous or hormonal system to effectors like muscles or glands, initiating responses to restore optimal conditions.

Question 13

What is an example of a control pathway that doesn’t occur as often as negative feedback and increases the original change in conditions?

Answer 13

Positive feedback.

Question 14

What is an ectotherm?

Answer 14

an organism that regulates its body temperature using external sources rather than internal metabolic processes.

Question 14

What is an example of positive feedback in the body?

Answer 14

Dilation of the cervix during childbirth.

Question 15

How do ectotherms regulate their body temperature?

Answer 15

control their body temperature by exchanging heat with their surroundings. They may expose themselves to the sun, orient their bodies to either minimize or maximize sun exposure, hide away from the sun, or increase breathing for heat loss via evaporation of water.

Question 16

Why can’t ectotherms rely on increasing their respiration rate to produce internal heat?

Answer 16

unable to increase their respiration rate to generate internal heat, thus they cannot rely on internal energy sources for thermoregulation.

Question 17

What is the defining characteristic of endotherms regarding body temperature?

Answer 17

maintain a constant body temperature regardless of external temperature changes.

Question 18

How do endotherms monitor changes in core body temperature?

Answer 18

use thermoreceptors to monitor core body temperature changes.

Question 19

What part of the brain coordinates responses to maintain optimum body temperature?

Answer 19

hypothalamus coordinates appropriate responses to restore the optimum temperature.

Question 20

Name two physiological responses endotherms use to control body temperature.

Answer 20

1. Shivering - contractions of skeletal muscles.
2. Sweat production to decrease body temperature via evaporation.

Question 21

How does shivering help endotherms regulate body temperature?

Answer 21

Shivering increases temperature as heat is released through contractions of skeletal muscles.

Question 22

What role do sweat glands play in regulating body temperature for endotherms?

Answer 22

produce sweat, which decreases body temperature through evaporation.

Question 23

How do endotherms manipulate their hair to regulate body temperature?

Answer 23

They can raise their hairs to provide insulation and reduce heat loss, or flatten them to minimize insulation and increase heat loss.

Question 24

Describe how arterioles contribute to the regulation of body temperature in endotherms.

Answer 24

Arterioles dilate to increase heat loss as blood flows closer to the skin, or constrict to reduce blood flow and minimize heat loss.

Question 25

What is the purpose of excretion in the body?

Answer 25

Excretion serves to remove metabolic waste products, which are often toxic and not needed by cells.

Question 26

What role does the liver play in excretion?

Answer 26

The liver breaks down harmful substances and toxic waste, converting them into less harmful forms for disposal via excretion.

Question 27

What is the structural composition of the liver?

Answer 27

composed of liver lobules, which are cylinders made of hepatocytes arranged in rows, connected at the center.

Question 28

How is each liver lobule connected to blood vessels?

Answer 28

Each liver lobule is connected to the hepatic vein, hepatic artery, hepatic portal vein, and bile duct.

Question 29

What is the function of the hepatic vein?

Answer 29

The hepatic vein takes deoxygenated blood away from the liver.

Question 30

What is the role of the hepatic artery?

Answer 30

The hepatic artery supplies the liver with oxygenated blood.

Question 31

What is the significance of the hepatic portal vein?

Answer 31

The hepatic portal vein contains the products of digestion.

Question 32

What is the function of hepatocytes?

Answer 32

break down toxic substances.

Question 32

What does the bile duct transport?

Answer 32

The bile duct is involved in the transport of bile, a fat emulsifier, to the gall bladder to be stored.

Question 33

What connects the central vein to the hepatic artery and portal vein?

Answer 33

Sinusoids, a type of capillary, connect the central vein to the hepatic artery and portal vein.

Question 34

What is the first step of amino acid excretion in the liver?

Answer 34

Deamination, the removal of the amino group from excess amino acids, leading to the formation of ammonia and organic acids.

Question 34

How do hepatocytes contribute to the bloodstream?

Answer 34

Toxic substances broken down by hepatocytes re-enter the blood, which then runs to the central vein.

Question 35

What is the role of sinusoids in the liver?

Answer 35

Sinusoids contain Kupffer cells, which break down old red blood cells and remove bacteria.

Question 36

What happens to the excess amino acids after deamination?

Answer 36

The acids undergo respiration to produce ATP or are converted to carbohydrates and stored as glycogen.

Question 37

How is ammonia converted to urea in the liver?

Answer 37

Ammonia is converted to urea by the addition of carbon dioxide in the ornithine cycle.

Question 38

How does the liver detoxify harmful substances like alcohol?

Answer 38

The liver breaks down alcohol into ethanal, which is further broken down into acetic acid.

Question 39

Describe the process of ultrafiltration in the kidneys.

Answer 39

Blood enters the kidney through the renal artery and passes through capillaries in the cortex. Waste products are filtered out of the blood into long tubules called nephrons.

Question 40

What is the main role of the kidneys?

Answer 40

Excretion of waste products, such as urea, in the form of urine.

Question 41

What is selective reabsorption and where does it occur in the kidney?

Answer 41

Selective reabsorption is the process where useful substances such as amino acids, glucose, and vitamins are reabsorbed back through the tubules in the medulla of the kidney.

Question 42

Where do the substances to be excreted pass through before reaching the bladder?

Answer 42

The substances to be excreted pass along the tubules and ureter before finally reaching the bladder.

Question 43

How does blood leave the kidneys after filtration?

Answer 43

Filtered blood exits the kidneys through the renal vein.