Question

6 contrast the breathing mechanisms in turtles, snakes, and crocodiles.
7 fill in table 21 - 3 with the appropriate characteristics for each group of reptiles, to compare the adaptations to different body shapes and lifestyles between turtles and snakes.
table 21 - 3 comparison of anatomical characteristics between turtles and snakes

	turtle	snake
eyelids (present or absent)
teeth (present or absent)
number of functional lungs
tracheal rings (complete or partial)
diaphragm (present or absent)
urinary bladder (present or absent)
location of urine storage
number of copulatory organs in male

Explanation:

1. Turtles use a combination of limb - movement and a modified rib - cage to breathe. Snakes rely on muscular contractions of the body wall to move air in and out of the lungs. Crocodiles have a more complex breathing mechanism with a diaphragm - like structure that helps in efficient gas exchange.

7.

Characteristic	Turtle	Snake
Eyelids (present or absent)	Present	Absent (have a transparent scale instead)
Teeth (present or absent)	Absent (have a beak)	Present
Number of functional lungs	2	Usually 1 (the right lung is more developed, left may be reduced or absent)
Tracheal rings (complete or partial)	Complete	Complete
Diaphragm (present or absent)	Absent	Absent
Urinary bladder (present or absent)	Present	Absent
Location of urine storage	Urinary bladder	Cloaca
Number of copulatory organs in male	1	2 (hemipenes)

Answer:

1. Turtles use limb - movement and rib - cage modifications for breathing. Snakes use body - wall muscular contractions. Crocodiles have a diaphragm - like structure for efficient gas exchange.
2. See the filled - in table above.