Topic 1 Flashcards
7 characteristics of life
Nutrition, metabolism, growth, response, excretion, homeostasis and reproduction.
Nutrition
Obtaining food, to provide energy and the materials needed for growth.
Metabolism
Chemical reactions inside the cell, including cell respiration to release energy.
Growth
An irreversible increase in size.
Response
The ability to react to changes in the environment.
Excretion
Getting rid of the waste products of metabolism.
Homeostasis
Keeping conditions inside the organisms within tolerable limits.
Reproduction
Producing offspring either sexually or asexually.
The Cell Theory
- All living organisms are composed of cells (or cellular products).
- The cell is the smallest unit of life.
- Cells only arise from pre-existing cells.
Striated Muscle
Exception to the cell theory, as individual cells fuse to form long multinucleated fibres.
Giant Algae
Exception to the cell theory, as certain species can be very large.
Aseptate Fungal Hyphae
Exception to the cel theory, as hyphae may be connected by a continuous cytoplasm.
Magnification
Magnification = image size (with a ruler) / actual size (according to scale bar)
Actual Size
Actual Size = Image size (with a ruler) / Magnification
Surface area and volume ratio
As a cell grows in size, volume increases faster than surface area. The SA:V ratio decrease with increasing cell size.
