B2-1

Most human cells, like animal cells, contain a nucleus, ribosomes. cytoplasm, cell membrane and mitochondria. 

Plant cells contain the same, however they also contain, chloroplasts and a permanent vacuole filled with cell sap. 

Cells are very small, you need a microscope to be able to see them. 

NUCLEUS: to control cell activities 

CYTOPLASM: where chemical reactions take place

CELL MEMBRANE: controls movement of materials in and out of the cell

MITOCHONDRIA: energy is released here during aerobic respiration 

RIBOSOMES: protein synthesis takes place here 

Plant and Algal cells have: 

CHLOROPLASTS: contain chlorophyll used for photosynthesis (chloroplasts absorb light energy to make food)

CELL WALL: made of cellulose for support]

PERMANENT VACUOLE: filled with cell sap

Bacteria cells are smaller than plant and animal cells. You are only able to see bacteria cells with a microscope. 

Yeast is a single-celled organism.

BACTERIA: - has a cell membrane and cell wall surrounded by cytoplasm

- No nucleus, genetic material in cytoplasm

- when it multiplies it turns into a colony, you do not need a microscope to see a bacterial colony

YEAST: -  has a nucleus, cytoplasm and cell membrane surrounded by cell wall

The structure of a cell is linked to its function. 

- if a cell has many ribosomes it is making alot of protein e.g gland cells which produce enzymes

- if a cell has many mitochondria it must need alot of energy e.g muscle cell, sperm cell

- cells with tails are able to move e.g sperm cell

- receptor cells have special structures which enable them to detect stimuli e.g cone cells in eye--sensitive to light 

- neurons specialised to carry impulses from receptors to the CNS

- plant cells with many chloroplasts will be photosynthesising 

- root hair cells increase surface of the root so it can absorb mineral ions and water 

Dissolved substances and gases can move in and out of cells by diffusion 

- it occurs more rapidly when there is a larger difference in concentration

- the net movement into or out of cells depends on the concentration of the particles on each side of the cell membrane

- concentration gradient=difference in concentration between two areas 

A tissue is a group of cells with similar structure and function.

Organs are made of several tissue types.

During the development of multicellular organisms the cells differentiate.

Animal Tissues: 

MUSCLE TISSUE: contracts to bring about movement 

GLANDULAR TISSUE: produces substances such as enzymes or hormones 

EPITHELIAL TISSUE: covers some part of the body 

Plant Tissues:

EPIDERMAL TISSUE: covers the plant 

MESOPHYLL: can photosynthesise 

XYLEM and PHLOEM: transports substances around the plant 

Organs are made of tissues. 

The stomach is an organ made of:

MUSCULAR TISSUE: to churn stomach contents

GLANDULAR TISSUE: to produce digestive juices

EPITHELIAL TISSUE: to cover outside and inside of stomach

The leaf, stem and root are plant organs that contain epidermal tissues, mesophyll, xylem and phloem. 

Groups of organs form organ systems to perform particular functions 

Digestive system has many organs, such as the small intestine

The food you eat must be changed from insoluable molecules to soluable molecules, then the soleuable molecules can be absorbed into the blood.

The digestive system is a muscular tube which includes:

GLANDS: like pancreas and salivary glands, these produce digestive juices

STOMACH and SMALL INTESTINE: where digestion occurs

LIVER: produces bile

SMALL INTESTINE: absorption of soluable foods occur here

LARGE INTESTINE: where water absorbed from the undigested food produces faceces