Cell Basics
The basic unit of all living organisms
a cell
Tissue that lines surfaces like the gut.
Epithelium
This cell carries oxygen using haemoglobin and has no nucleus.
a red blood cell
This cell has a long extension to absorb water and minerals.
A root hair cell
Group of similar cells working together.
A tissue
Small structures found in all cells where proteins are made
ribosomes
Tissue that contracts to move the body.
Muscle tissue
These tiny hair-like structures move mucus.
A cilia
This cell transports water and is strengthened by lignin.
a xylem vessel
Several organs working together.
An organ system
The structure that controls cell activities and contains DNA
The nucleus
Tissue that transports substances.
Blood
This cell has a long axon to transmit impulses.
a motor nerve cell
This cell contains many chloroplasts for photosynthesis.
a palisade mesophyll cell
Correct order from smallest to largest.(Cell, Organ System, Organelle ,Organism, Tissue.)
Organelle → Cell → Tissue → Organ → System → Organism
Unit used to measure cells
A micrometre
Tissue that transmits nerve impulses.
Nervous tissue
Why do red blood cells lack a nucleus?
To make more space for haemoglobin.
Why do xylem vessels have no end walls?
To form continuous tubes for water flow.
Which level includes structures like mitochondria and ribosomes?
The organelle level
If a cell is 50 µm long, how many fit in 1 mm?
20 cells
Tissue that supports and protects organs.
Skeletal tissue
What adaptation allows sperm cells to reach the egg?
They can swim using a tail (flagellum).
Why do root hair cells have large surface area?
To increase absorption of water and minerals.
Why can’t a single cell carry out all the functions of a complex multicellular organism?
Because cells are specialized and lack all structures needed for every life function, so they depend on other cells and organization levels.