Grade 11 biology notes based off of 'McGraw-Hill Ryerson Biology 11' textbook and in-class lectures. Contact @samanthaguu on Instagram for a shared version on google drive with interactive links and document outline.
, 7.1 - Adaptation and Variation
Adaptations and Survival
Evolution:
- The relative change in characteristics of populations that occurs over successive
generations
- Does not explain how life began
- Happens due to a combination of environmental pressures and variation within
species
- Environmental pressures:
- Limit a species ability to survive and reproduce
- Ex. Severe weather, disease, competition
- Variation:
- Comes from independent assortment, g enetic recombination and
mutations
- Mutations: Changes in the DNA of an organism; either
from errors during mitosis (not effect on species) or
meiosis (heritable, can cause variation) or mutagens
- Extinction: Occurs when a species was poorly adapted to a changing set of
conditions and perished
Types of Variation
1. Positive:
- Increase chance of passing on traits; can eventually result into
adaptations
2. Negative:
- Decreased chance of passing on traits
3. Neutral:
- No impact on ability of passing on traits
Adaptations
- Traits that increase the chance of survival and successful reproduction in a
particular environment
- Arise from new alleles that develop due to mutations which eventually cause
allele frequencies of a population to change over time
Antibiotic-Resistance in Bacteria:
- Example of selective advantage
- Mutation may make a bacteria resistant to antibiotics; they can then pass on
these gene through reproduction, conjugation or by taking up DNA that has been
released upon the death of another bacterium
- Similar concept w/ insecticide resistance
, Types of Adaptations:
1. Structural Adaptations:
- Physical features of an organism that help it survive and reproduce
- Ex. Talons, night vision
2. Behavioural Adaptations:
- Behaviours that help an organism survive
- Ex. Mating calls, migration, living/hunting in groups
3. Physiological Adaptations:
- Internal systems or processes that improve survival and reproductive
success
- Ex. Venom, phototropism, body temperature regulation, hibernation
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