chapter 6 Organisms exchange substances with their environment

Question 1

Why is there a higher demand for transport of waste out of cells in larger organisms?

Answer 1

Due to their higher metabolic rate.

Question 2

What adaptations do insects have to limit water loss?

Answer 2

• Small surface area to volume ratio where water can evaporate from.
• They have a waterproof exoskeleton.
• Have spiracles, where gases enter and water can evaporate from, can open and close to reduce water loss.

Question 3

What are spiracles?

Answer 3

Round valve like openings, along the length of the abdomen. Oxygen & carbon dioxide enter and leave via spiracles. The trachea attach to these openings.

Question 4

What is the trachea?

Answer 4

A network of internal tubes . They have rings within them to strengthen the tubes and keep them open.

Question 5

What are tracheoles?

Answer 5

Trachea branch into smaller tubes called tracheoles. These extend throughout all the tissues in the insect to deliver oxygen to respiring cells.

Question 6

What is the gas exchange surface in fish?

Answer 6

Gills

Question 7

What are the gills made up of?

Answer 7

Stacks of gill filaments. Each gill filament is covered in gill lamellae.

Question 8

What creates the large surface area in the gills?

Answer 8

• The 4 layers of gills on both sides of head.
• Gill filaments and gill lamellae.

Question 9

How is there a short diffusion distance in fish?

Answer 9

Gill lamellae are very thin. In every lamellae there is a capillary network which is close to outside where oxygen is diffusing in from.

Question 10

How is the concentration gradient maintained in fish?

Answer 10

Due to the countercurrent flow mechanism.

Question 11

What are xerophytic plants?

Answer 11

Plants that are adapted to survive in environments with limited water.

Question 12

Describe the process of inspiration (inhaling)

Answer 12

-External intercostal muscles contract and pull ribs outwards and upwards.
-Internal intercostal muscles relax.
-Diaphragm contracts
-Lung vol increases to decrease pressure.
-Air moves into lungs, from atm pressure into lower pressure

Question 13

Describe the process of expiration (exhaling)

Answer 13

-External intercostal muscles relax.
-Internal intercostal muscles contract (pull ribs downwards & inwards)
-Diaphragm relaxes.
-Lung vol decreases to increase pressure.
-Air moves out lungs .

Question 14

What are alveoli and what do they do?

Answer 14

Tiny air sacs which provide a very large surface area for gas exchange.

Question 15

How does the alveolar epithelium provide a short diffusion distance?

Answer 15

The alveolar epithelium cells are very thin.