Download 9Aa.Environmental Variation-Summary Notes

9Aa: Environmental Variation
Environment: the objects, or conditions by which one is surrounded.
Variation: the differences in characteristics between organisms of the same
species.
Biotic and abiotic factors are what make up ecosystems.
Biotic factors
Abiotic factors
are living things within an ecosystem.
are non-living components.
plants, animals, and bacteria.
water, soil, and atmosphere.
Environmental and Inherited Variation:
Some variation within a species is due to the environment, and some variation
is inherited.
1. Environmental Variation:
Environmental
is the differences in characteristics that are caused
variation
by external factors in an organism’s surroundings.
Environmental factors such as:
diet, lifestyle choices, climate, accidents, culture, religion, scars, language,
tattoos.
For example:
1. tattoos are not inherited; they are a result of a lifestyle choice.
2. diet you will become heavier if you eat too much food, and you will
become lighter if you eat too little.
3. A plant in the shade of a big tree will grow taller as it tries to reach
more light.
4. flower colour in hydrangeas:
(these plants produce blue flowers in acidic soil and pink flowers in alkaline soil).
2. Inherited variation
Inherited
variation in a characteristic that is a result of genetic
Variation:
information from the parents.
Children usually look a little like their father, and a little like their mother,
but they will not be identical to either of their parents.
This is because they get half of their DNA and inherited features
from each parent.
Each egg cell and each sperm cell contain half of the genetic information
needed for an individual.
When these join at fertilization a new cell is formed with all the genetic
information needed for an individual.
Examples of inherited variation in humans:
•
eye colour
•
hair colour
•
skin colour
•
lobed or lobeless ears.
•
ability to roll your tongue.
Variation can be inherited or environmental
Sex (Gender) is an inherited variation
because whether you are biologically male or female is a result of the genes
you inherited from your parents.
Environmental and Inherited causes:
Some features vary because of a mixture of inherited causes and
environmental causes.
For example, identical twins inherit exactly the same features from their
parents. However, if you take a pair of twins and twin 'A' is given more to
eat than twin 'B', twin 'A' is likely to end up heavier.
Weight and height are common examples of characteristics that are influenced
by both genetic and environmental factors.
Properties
Examples
Continuous variation
Discontinuous variation
No distinct ‫ متميزة‬categories.
-Distinct categories.
-No limit on the value.
- No in-between values.
- Tends to be quantitative.
-Tends to be qualitative.
-height -weight -heart rate
- tongue rolling – fingerprints
-finger length - leaf length
- eye colour - blood groups
Bar graph
Line graph
Representation
A lot of genes and the
environment
Controlled by
→range of phenotypes
between 2 groups extremes,
‫مجموعة من األنماط الظاهرية بين مجموعتين‬
‫متطرفتين‬
A few genes
→ a limited number of
phenotypes with no
intermediates.
‫عدد محدود من األنماط الظاهرية بدون وسيط‬
What is Classification?
Living organisms are arranged into different groups and subgroups, by looking
at the similarities and differences between them.
The level of hierarchy in the system of classifying organisms is:
Kingdom, Phylum, Class, Order, Family, Genus, Species
Species
A species is a group of similar organisms that can breed with one another to
produce fertile offspring.
For example, humans are one species and dogs are another species.
Individuals of the same species can reproduce to make more individuals of the
same species.
Two individuals belonging to different species cannot normally reproduce
together.
If they do, their offspring is often infertile and unable to reproduce.