Molecules To Organisms Flashcards
Why is Nitrogen, Oxygen, Carbon and Hydrogen the most suitable elements for life?
- They are the most abundant in the universe.
- H and O are elements of water.
- They have empty outer orbitals.
- Carbon is able to undergo orbital hybridisation.
What four molecules are humans composed of?
Nitrogen, Oxygen, Carbon and Hydrogen.
State three features of a Protozoa.
- They ingest whole bacteria.
- Capable of directional movement.
- They lack a rigid cell wall.
Name two types of Protozoa and their functions.
Ciliate and flagellate - They can swim through water by a beating action of hair-like appendages.
Amoeba - They do not swim but can creep along surfaces by extending a portion of the cell, called the pseudopod, and then allowing the rest of the cell to flow in this direction.
Explain chemotaxis.
It is triggered by the chemical signal cyclic AMP. Those cells making the stalk die and those released as spores will survive.
State four main features of animals.
- Eukaryotic and multicellular.
- Heterotrophic (cannot fix carbon so need to eat organic compounds).
- They are motile.
- Embryos pass through a blastula stage.
Describe the four stages of animal embryonic development.
- Determination - Sets the fate of the cell.
- Differentiation - Different cell types arise.
- Distribution - The organisation and spatial distribution of differentiated cells.
- Growth - An increase in body size by cell division and expansion.
Define totipotent cell.
A cell that can differentiate into any type of cell.
Define pluripotent cell.
They come from the inner cell mass of a blastocyst.
Pluripotent stem cells can give rise to all cells that are derived from what three germ layers?
Ectoderm, mesoderm and endoderm.
Define grastrula.
It’s formed by the rearrangement of blastula cells into the three germinal layers, which consequently become the various tissues and organ systems of the animals body.
Multiple signalling proteins are also known as what? What do they do?
They are known as growth factors. They drive stem cell differentiation into different tissues.
What does myostatin lead to?
Increase in the mass of muscle tissue.
Define morphogenesis.
The development and differentiation of the structures and form of an organism; specifically the changes that occur in the cells and tissues during embryonic development.
