Page 122 - Science Class 06

Unicellular : Organisms made up of only a single cell
Multicellular : Organisms made up of many cells
Vertebrate : Organisms with backbone and other bones

Invertebrate : Organisms having no bone or cartilage in their body
Bone : Very hard materials made up of living cells, calcium phosphate and
collagen
Rib : Cage like structure of bones present inside our chest

Tendons : Inelastic fibres that attach muscles with bones
Joints : Where two or more bones join

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i Vertebrates are the most advanced of species in the animal kingdom.
i Most of the multicellular orgnisms are vertebrates.
i Ribs are attached to vertebrae at the back which curve around to form a cage.
i Human skeletal system consists of bones of the skull, the backbones, ribs and limbs.
i All the animals whether unicellular or multicellular perform various life processes to live.

I The human excretory system functions to remove wastes from the human body.

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A. Tick ( ) the correct op on. 3
1. Which of the following is not a mul cellular organism?
(a) Dog (b) Earthworm
(c) Fish (d) Hydra

2. Which of the following organisms is invertebrate?
(a) Snake (b) Fish
(c) Earthworm (d) Bird

3. How many bones does our spine consist of?
(a) 12 (b) 24
(c) 36 (d) 48
4. Which of the following joints allows our appendages to move only back and forth?
(a) Hinge joint (b) Ball-and-socket joint

(c) Pivot joint (d) None of these
5. Which of the following organs does not involve in respiratory system of human beings?
(a) Trachea (b) Bronchi

(c) Lungs (d) Nerves

122 Science-6