Biology - Chapter 1 - Principles and the basic structures of life

bacteria

unicellular microorganisms some of which are pathogenic in humans, animals and plants

cell membrane

A selectively permeable membrane surrounding the cell and controlling the entry and exit of materials

chloroplast

contains green pigment chlorophyll, the site of photosynthesis

nucleus

controls what happens in the cell, where the chromosomes are located

DNA

A complex molecule containing the genetic information that makes up the chromosomes.

The adaptation of the cells lining the small intestine

Has a large surface area to absorb more food faster

Why are unicellular organisms at a disadvantage?

They do not live for long as it gets tired easily and there is no other cell to replace it.

Epithelium

Forms the coverings and linings of the body

adaptation

A feature of an organism's body which helps it to survive.

cell

Basic unit of life

unicellular

A single celled organism

multicellular

Made up of more than one cell.

cell wall

provides support and prevents bursting by osmosis. Keeps the plant cell turgid

cytoplasm

the living substance inside a cell, where chemical reactions take place

mitochondria

where respiration takes place (powerhouse)

specialised cell

A cell that has become differentiated to carry out a particular function, eg red blood cell.

tissue

A group of similar cells that perform the same function.

vacuole

a space in the cytoplasm of plant cells that contains cell sap

prokaryotic cell

cell without a nucleus that is found in single-celled organisms, ex bacteria

eukaryotic cell

cell with nucleus and organelles present. Found in all other living organisms apart from bacteria.

Animal cell division step 1

Nucleus divides

Animal cell division step 2

The cytoplasm pinches off between the two nuclei and two daughter cells are formed.

Animal cell division step 3

Two daughter cells are now individual, where one of them becomes a specialized cell.

Plant cell division step 1

The nucleus divides to become two, and a new cell wall forms to separate them.

Plant cell division step 2

One of the cells enlarges, vacuoles form and force the cell to expand, and eventually the two cells separate

The adaptation of red blood cell

No nucleus for more space for haemoglobin to carry more oxygen

The adaptation of a muscle cell

Has a lot of mitochondria

Adaptation of nerve cell

Long cytoplasm to carry messages easily

Adaptation of palisade cell

Contains chloroplasts

Adaptation of root hair cell

Bigger surface area to absorb more water and nutrients from the soil

How do unicellular organisms carry out all the functions?

They have a large surface area to volume ratio

Multicellular organisms (animals) consist of:

organelles-cells-tissues-organs-organ systems-organism

Connective tissue

Found between the body organs binding the parts together

Muscle tissue

Contracts, resulting in movement

Nervous tissue

Transmits messages/nerve impulses

Mesophyll tissue

Photosynthesis occurs here

Epidermis (plant tissue)

The outer layer of the root