GCSE Biology

Biology Revision (B1):

(TOPIC 1)

CLA**IFICATION:

Heterotrophic: Eats other things.

Autotrophic: Makes its own food by photosynthesis.

Saprophytic: Digests other organisms outside of its body.

Uni cellular: Made of just one cell.

Multi cellular: Made up of many cells.

Cellular:

Cell Walls:

Nucleas:

How it eats:

Uni

Multi

Yes

No

Yes

No

Heterotrophic

Autotrophic

Saprophytic

Animalia

✓

✓

✓

✓

Plantae

✓

✓

✓

✓

Fungi

✓

✓

✓

✓

Protoctists

Most

N/A

✓

N/A

Prokaryote

✓

✓

[Bacteria are not cla**ified as living since they do not grow or feed.]

The Order of Cla**ification:

• Kingdom
• Phylum
• Cla**
• Order
• Family
• Genus
• Species

Chordata: Have supporting rod running through the body. [Vertebrate / Invertebrate]

Homeotherm: Warm-blooded.

Poikilotherm: Cold Blooded.

Oviparous: Lay eggs.

Viviparous: Give birth to live young. [Internal Fertilisation / External Fertilisation]  

 

 

 

 

 

 

SPECIES:

Hybrid: Two species, closely related, interbreed and produce hybrids, which are usually infertile.

Naming Species:

Binomial Name: 1st Name - Genus

                           2nd Name - Species

Useful: 

• They can tell us how closely related two different species are.
• Can be used in all languages.

Difficulties: 

• Not all hybrids are infertile.
• Some organisms [Bacteria & Fungi] reproduce when there is just one parent.
• Mallard ducks can hybridise with other closely related species to produce fertile [hybrid] offspring.
• Some gulls form ring species - neighbouring species can interbreed.

VARIATION:

Genetic Characteristics: Characteristics which are pa**ed down from parent DNA or caused by mutilation.

Environmental Characteristics: Characteristics acquired during an organisms lifetime caused by its environment. e.g. Colour, accent etc.

EVOLUTION:

Evolve by Natural Variation:

• Variation in Species X…
• Individuals in Species X compete for limited resources. e.g. food, space etc.
• The individuals in Species X which had the best adaptations are most likely to survive…
• … and reproduce…
• … and pa** on their genes to their offspring.
• Over many generations this resulted in a gradual change in Species X. Eventually it evolved into Species Y.              

New Evidence for Evolution: Rats that have become resistant to rat poison Warfarin.

SPECIATION:

The proce** of becoming a new species. This often happens when there is some sort of geographic isolation.

GENES AND GENETIC INHERITANCE:

Homozygous: Both alleles are the same.

Heterozygous: Both alleles are different.

GENETIC DISORDERS:

1. Sickle Cell Decease: [rece**ive]

** - Healthy

** - Healthy but a Carrier

**-has Sickle Cell

Symptoms: 

• Become tired very quickly
• Short of breath
• Painful joints because their red blood cells stick together.

2. Cystic Fibrosis: [rece**ive]

FF - Healthy

Ff - Healthy but a Carrier

ff - Has Cystic Fibrosis

Symptoms:

• Produce sticky mucus in lungs
• Lung infection
• Difficulty digesting food

…