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B1 You and Your Genes

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Nitrogen bases: Adenine pairs with Thymine Guanine pairs with cytosine. Human male chromosome s. DNA is a double helix Genetic instructions are in the form of a code made up of 4 bases. DNA with bases. Inheritance- Parents who are both carriers of the Cystic fibrosis allele (c).

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Nitrogen bases:

Adenine pairs with Thymine

Guanine pairs with cytosine

Human male chromosomes

DNA is a double helix

Genetic instructions are in the

form of a code made up of 4 bases

DNA with bases

Inheritance- Parents who are both carriers of the Cystic fibrosis allele (c).

Parents Cc x Cc

Gametes C or c x C or c

(egg/sperm) C c

Possible Outcomes C

75% Normal c

25% sufferers

B1 You and Your Genes

Lobed ears are dominant over ears with no lobes

Cytoplasm: chemical reactions take place

Cell membrane: Controls movement into and out of the cell

Nucleus: contains genetic information

Mitochondria: Respiration takes place providing energy

Cystic Fibrosis

Caused by recessive allele (so two copies of allele are needed).

A thick sticky mucus is produced affecting air passages and digestive systems

Protein synthesis:

Each gene codes for

a particular protein


Genetic Testing

To determine any faulty alleles being passed on

Huntington's Disease

Caused by dominant allele (one copy of allele are needed).

Loss of memory and neurone damage in the brain


Used to screen embryos for faulty alleles

Variation – caused by dominant/recessive alleles and environment

Stem cells - cells with no specific function. Can be turned into any cell


Heart pumps blood around the body

Arteries transport blood away from the heart

Veins transport blood into the heart

Capillaries exchange materials with tissues

Producing antibodies

Vasoconstriction and Vasodilation

Step 2: The cell produces antibodies

to “fit” the pathogen


Monitored by thermoregulatory centre in brain and receptors in skin.

Too Hot

-hair lies flat

-blood vessels dilate so heat lost through skin

-sweat produced

Too Cold

-Goosebumps & hairs trap air

-blood vessels constrict

-no sweat

-shiver, respiration releases heat

B2 Keeping Healthy

Step 1: The lymphocyte “sees” the pathogen (microbe)

Step 4: The pathogens are “eaten” by the white blood cells

Step 3: The antibodies fit onto the pathogens and cause them to “clump”


Damaged cilia in a smoker’s air way

Resistant Bacteria's – these are bacteria's that have mutated and antibiotics no longer are able to kill them.

Vaccines – dead or live proteins injected into the body. The body will make antibodies for the antigens of the microbes.

Risk Factor – when you increase the risk of getting the disease by doing the factor i.e. drinking alcohol


A factor that can cause an outcome. Correlation means that there is a common link between a factor and outcome.

Water Homeostasis – controlled by negative feedback of ADH.



What evidence is there that evolution is happening?

  • How are human beings different from apes?
  • bigger b_____
  • w_____ upright


D______ proposed the theory of e______ to explain how species change over time. There is v_______ between individuals, those that are better a_______ are more likely to s________ and r________, passing on favorable characteristics.

  • Fossil record is incomplete because:
  • Some body part decay quickly
  • Fossilisation is rare
  • There may still be fossils we have not found


Ocean, dessert, grass land,

rain forest


Farm land, Aquarium, green house

The up and down pattern of predator and prey

population is called cyclic fluctuations


Believed that acquired characteristics can be inherited

Photosynthesis happens only during day but

respiration happens both during day and night

B3 Life on Earth

The presence or absence of an indicator species is

used to estimate levels of pollution Example: Lichens



  • CHARLES DARWIN: Developed theory of natural selection based on survival of fittest
  • Genes pass on the successful characteristics to the next generation
  • What resources are plants and animals in competition for?
  • Space
  • Food
  • Mate
  • Causes of extinction:
  • increased c_______
  • New p________
  • e_________ change
  • new d_________

Adaptation: features which help a plant

or animal survive in an extreme

environment,. Example: Polar bear, Camel and cactus

Sustainable development

is taking things from the

environment but leaving

enough behind to

ensure a supply for

the future and

prevent damage



MUTUALISM: When both

Organisms benefit, example:

Pea plant and

nitrogen – fixing bacteria


“Species” means “a group of similar organisms” which are capable of interbreeding to produce fertile offspring, e.g. dogs


Hybrids are the result of breeding two

animals form different species, they

cannot reproduce and are sterile.

Example: Tiger +Lion = Tigon

Classifying organisms


Interspecific Competition – between two different species

Intraspecific Competition – between the same species








Have backbone

No backbone



Origin of Species

Nitrogen & Carbon Cycle – how these elements form a cycle, uses of decomposition, respiration, consumption and photosynthesis






Biodiversity – different species living in the same habitat/ecosystem.