Reptiles

Question 0

What is diapsida composed of?

Answer 0

The archosaurs and lepidosaurs.

Question 1

Amniotes developed the cleidoic egg to give freedom from the water. What is the shell made of in both archosaurs and lepidosaurs?

Answer 1

Archosaurs = 95% calcium carbonate
Lepidosaurs = leathery shell made of protein

Question 2

What is archosauria composed of?

Answer 2

The crurotarsans and ornithodirans.

Question 3

What is lepidosauria composed of?

Answer 3

The squamates and the rhyncocephalians.

Question 4

Eggs display temperature dependant sex determination. In crocodiles how does this work?

Answer 4

Hotter = makes
Colder = females

This is the opposite in turtles.

Question 5

The diapsids have 2 major ways of giving birth. What are they?

Answer 5

1. Oviparity = egg laying

2. Ovivivaparity = mother gives birth to live young from eggs that have hatched within her body

Question 6

All lepidosaurs and crocodiles are ectothermic. What advantages does this have?

Answer 6

They do not need to expend energy on thermoregulation. As all energy is derived from a free source more can be converts to biomass, so they need less food.

Question 7

How do ectothermic diapsids thermoregulate?

Answer 7

1. Behavioural methods

2. Physiological methods

Question 8

How do nocturnal reptiles obtain heat?

Answer 8

From rocks.

Question 9

Why do reptiles shed their skin?

Answer 9

Keratin is a dead protein that cannot grow to accommodate size changes.

Question 10

Water loss across the eyes is substantial. How have reptiles solved this problem?

Answer 10

Evolved the Brille, a scale that grows across the eyelid.

Question 11

Scaly skin is derived from the epidermis, but where is body armour derived from?

Answer 11

Osteoderms (dermal bone cells)

Question 12

Reptiles are said to have ‘respiration with locomotion’. What does this mean?

Answer 12

In a sprawling gait, the body waggled from side to side due to axial muscle contraction. This alternately ventilates each lung due to compression with each step.

Question 13

Do reptiles have a diaphragm?

Answer 13

No.

Question 14

What kind of breathing do crocodiles have?

Answer 14

Cuirassal breathing

Question 15

In chelonians the ribs are fused in the shell and cannot expand/contract in breathing. How have they overcome this?

Answer 15

They have muscles that attach from the inside of the shell to the stomach. These push the stomach into the lungs to expel the air.

Question 16

Snakes have reduced/lost their left lung as a result of elongation. How do they breathe?

Answer 16

The right lung is v. long but only the anterior part is oxygenated. The posterior part acts as a bellow.

Question 17

What kind of heart do reptiles have?

Answer 17

A 4-chambered heart

Question 18

What is the lens like in the reptilian eye?

Answer 18

Thin, soft and distortable. It DOES NOT MOVE but can change shape.

Question 19

What is the parietal organ?

Answer 19

A light-sensing/seasonality organ.

Question 20

How do reptiles ‘taste the air’?

Answer 20

Via the vomal nasal organ.

Question 21

Secondary limb loss is v. common in reptiles. How many times has it occurred independently?

Answer 21

Approx. 60

Question 22

Do reptiles masticate?

Answer 22

No, but static feeding pressure on the anterior teeth means they can powerfully close their jaws and eat a wide range of prey.

Question 23

Do reptiles have a thickened cornea?

Answer 23

Yes, it helps the eye to focus.