Invert summary

Question 1

What is an extended phenotype?

Answer 1

Organisms can create something (e.g. a web), which is completely necessary to survive, but isn’t necessarily in the genotype.

Question 2

What is the unit of life?

Answer 2

Genes?
They control life and are selected by natural selection. Gene frequency can be measured, but they are useless without a cell and therefore genes fail the three criteria test.

Cells?
All living cells have them, but a cell in a multicellular organism is nothing without the rest of the organism and therefore cells fail the three criteria test. Most organisms are unicellular so cell and organism aren’t mutually exclusive.

Organisms?
The unit of natural selection, and have cognition. But they are dead without their environment and therefore fail the three criteria test.

Habitats?
They have a boundary, are capable of maintaining themselves and are able to regenerate. They are the unit of life.

Question 3

Important events in evolution?

Answer 3

1. Semi-permeable membrane: Protection & Awareness of the environment. Allows for selective uptake, and concentration of molecular components.
2. RNAs: Information storage, control, novelty & variation, catalysis and the genetic code.
3. Photosynthesis: Life now has an infinite amount of energy to play with, the use of water as the electron donor results in the Great Oxidation Event and aerobic respiration recycles the carbon dioxide and makes life work faster.
4. Endosymbiotic events: Mitochondria & the creation of the proto-eukaryotic cell, emergence of the eukaryotic cell which made multicellularity possible.
5. Multicellularity: Increases size of organisms and complexity. More things to go wrong, but opportunity for diversity and colonisation of land.
6. Sexual Reproduction: Has evolved many times, and has persisted despite the twin cost of sex (offspring only shares half of the genome).
7. Sight: Only 6 of the 38
   phyla of animals have eyes, but 95% of animal species have eyes. Eyes appear in the fossil record just before the Cambrian Explosion – drove the expansion.
8. Colonisation of land by lichens: First terrestrial organisms led to the Neoproterozoic Oxidation Event, followed by the plants & animals. Increase in species diversity.
9. Flight: Defies gravity. One of the reasons for diversity of insects. Lost as many times as it was gained.
10. Trees: Evolved at least 4 times. Resulted in first wildfires.
11. Seeds: The 30,000 year survival capsule. 90% of plants have them, most of them are eaten and agriculture would be impossible without seeds.
12. Architecture: Increased the human carrying capacity of Earth 200-fold. Only ants, also social, are also farmers. Evolved 9 times independently. Only possible due to the emergence of language, social behaviour, domestication of fire.

Question 4

How do sessile animals breed?

Answer 4

Larvae are used to colonise new areas

1. Broadcast spawning (e.g. Corals). Species release all eggs & sperm, coordination of species in a certain area
2. Long penis (e.g. Barnacles). Penis extends to be several times the size of the Barnacle.
3. Spermcast (e.g. Bryozoa). Lophophore of female filters dilute sperm from water & eggs are kept in Bryozoa.