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S3 Biology
Unit 2: Multicellular Organisms
Pupil Summary Notes
1. Multicellular organisms are made up of many different types of cells.
2. Cells group together into tissues. Tissues work together as organs and
organs form organisms.
3. Two eyes are better than one. This is called binocular vision.
4. The ear is made of several structures. These include the middle ear
bone, the semi circular canals, the eardrum, the cochlea and the
auditory nerve.
5. The semi circular canals maintain balance. They are suited to their job
because they can detect movement in three different directions; up and
down, side-to-side, and rotating.
6. The body is able to maintain a constant temperature of 37 degrees.
This is an example of homeostasis.
7. If we are too cold then our blood vessels constrict, we shiver and our
skin hairs contract to stand erected.
8. If we are too hot then our blood vessels dilate, we sweat and our skin
hairs relax to lie flat on our skin.
9. Our body can also regulate blood sugar content and water balance.
Water balance regulation is called osmoregulation.
10.
Asexual reproduction is when only one parent is involved.
11. Sexual reproduction is when two parents are involved and depends on a
male sex fertilising a female sex cell to form a zygote.
12.
Bacteria can reproduce sexually or asexually. Bacterial asexual
reproduction involves a process called binary fission. This produces
identical offspring. Bacterial sexual reproduction involves process called
conjugation, which produces non-identical offspring.
13.
Runners and tubers are examples of natural asexual reproduction
in plants.
14.
Cuttings and grafting are examples artificial asexual reproduction
in plants.
15.
A plat seed has three parts. The food store supplies the growing
embryo with energy. The seed code protects the embryo. The embryo
grows into a new plant.
16.
A seed needs specific conditions, such as a suitable temperature,
water and oxygen, in order to germinate.
17.
A honeybee’s anatomy is made of three parts, the head, the
thorax and the abdomen.
18.
A frog develops from frogspawn. It first grows into a tadpole,
then a two-legged tadpole, and then into a froglet and then an adult
frog.
19.
Learned behaviour is taught through experience. An example is
wolfs teaching there pups how to hunt.
20.
Instinctive behaviour is characteristic of a species and is
associated to a specific environmental stimulus.
21.
Animals can change their behaviour in response to environmental
triggers. Examples include geese migrating in winter, or cockroaches
being active at night time.
22.
Tongue rolling, eye colour and petal colour are examples of
inherited characteristics.
23.
‘Phenotype’ describes the possible forms of the same
characteristic, for example blue or brown eye colour.
24.
‘Genotype’ describes the types of genes an organism has.
25.
‘Allele’ describes the different forms of a gene that exist in an
organisms’ DNA.
26.
A dominant allele will always be seen in an organism’s phenotype. It
will mask the effects on a recessive allele. A recessive allele can only be
seen if the organism has two copies of the recessive allele.