Osteichthyes

Question 1

Characteristic of bony fish

Answer 1

Bone in their skeleton 
Swimbladder or lung 
Tre scales 
Homocercal tail
Mouth terminal

Question 2

Osteichthyes are divided in two subclasses

Answer 2

Lobe finned fish

Ray finned fish

Question 3

Characteristics of sarcopterygians

Answer 3

Have lungs for gas exchange
Enae on teeth
Lobe finned

Question 4

Actinopterygains

Answer 4

Ray finned fish(fins lack muscular lobe)

Question 5

Fins function —-

Answer 5

Movements,camouflage,streamlining

Question 6

Outer covering of bony fish

Answer 6

• Mucus:reduces friction and prevents infection.

- scales :can tell age of fish ,like roof shingles

Question 7

Type of outer cover

Answer 7

Ganoid 
Placoid
Ctenoid
Cycloid
Myomer

Question 8

Characteristics of labeo (Rohu)

Answer 8

Scales are cycloid and head devoid of scale.
Lips are lobate.
Jaws devoid of teeth ,3rows

Question 9

What does the digestive system do ?

Answer 9

changes food into materials that nourish the body cells

eliminates materials that are not used

Question 10

Organs of the Digestive System

Answer 10

jawed mouth with a tongue and teeth

fish cannot move its tongue
fish have their teeth rooted in the jaws

Pharynx
a short tube behind the mouth Esophagus
a tubelike organ - expands easily, which allows the fish to swallow
its food whole

Stomach

Liver 
- Bile-producing digestive gland • 
Gall Bladder - Small sac containing the bl • Pyloric cecum - cul-de-sac related to the intestine - where a part of digestion mainly occurs, as well as fermentation 
• Intestines 
Anus

Question 11

Pyloric caeca

Answer 11

Present in bony fish
Work as accessory food reservoirs.
enhance the absorptive area.

Question 12

How does digestion work in fish?

Answer 12

Fish use their teeth to seize prey or to tear off pieces of their victim’s flesh. Most fish also have teeth in the pharynx, which they use to crush or grind food.

Question 13

Grazer

Answer 13

Fish that feed primarily on seaweeda and other plant

Question 14

Mode of nutrition in bony fish

Answer 14

Suspension feeders مغذيات التعلق
Scavengers
Detritivores
Parasitesالطفيليات

Question 15

Difference between scavengers & detritivores

Answer 15

scavengers: make place clean eat tiny animal
detritivores: make place clean but can’t eat tiny animal

Question 16

What is the meaning of gill filaments& gill rakers & gill arches

Answer 16

gill filaments :Sit of gas exchange

gill rakers:appendages along the front edge of the gill arch

gill arches: support the gills

Question 17

What is the meaning of swim bladder

Answer 17

Gas filled chamber that allow the bony fish to remain floatinf in the water

Question 18

Water flows across the gill filaments and oxygen is removed and passes into the blood by———-

Answer 18

diffusion الانتشار

Question 19

To increase the efficiency of oxygen uptake a ———-

Answer 19

Countercurrent method التيار المعاكس

blood flows through the lamellae in a direction opposite to the water flow through the gill filaments. Countercurrent flow ensures a steady oxygen. Countercurrent gas exchange

Question 20

COUNTER-CURRENT FLOW:

Answer 20

water and blood in the gills flow in opposite directions

Question 21

The function of counter current flow

Answer 21

→ maintains a favourable concentration gradient for diffusion of both gases

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