Biology GCSE (B1)

Cards covering all involved in the Biology B1 Exam

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  • Created by: Katherine
  • Created on: 20-12-11 10:25

Key Language

Key Language:

Nuleus:The positively charged central core of an atom, containing most of its mass.

Chromosomes: are made from long, coiled molecules of DNA. A gene is a shorter region of DNA that carries the genetic code for a particular characteristic or cell activity.

Genes: (in informal use) A unit of heredity that is transferred from a parent to offspring and is held to determine some characteristic of the...: "proteins coded directly by genes"( in technical use) A distinct sequence of nucleotides forming part of  a chromosome.

DNA: Deoxyribonucleic acid, a self-replicating material present in nearly all living organisms as the main constituent of chromosomes. The fundamental and distinctive characteristics of someone or somthing, esp. when regarded as unchangeable.

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The Same & Different

Explain where Genes are found and their function:

The nucleus of a cell contains chromosomes that carry genetic information. Most body cells have the same number of chromosomes, but this varies between species. Human body cells, for example, each have 23 matching pairs of chromosomes.

Chromosomes are made from long, coiled molecules of DNA. A gene is a shorter region of DNA that carries the genetic code for a particular characteristic or cell activity. 

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The Same But Different

Characteristics: Characteristics through genes: Eye colour

Characteristics through environmental factors: Skin Tone

Asexual Reproduction resulting in Clones:

Asexual reproduction only requires on parent. All the offspring are genetically identical to each other and their parent. They are called clones.

Plant Clones: Many plants produce clones all by themselves- this means that the produce exact genetic copies.

Gardeners often take cutting from a plant  and plant them to produce identical copies.

Commercial Cloning often involves tissue culture:

1)Choose plant 2) Remove tissue 3) Grow tissue in a medium containing nutrients and growth hormones. This is done in aseptic conditions.

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What Makes You The Way You Are

Reproductive Cells:

Reproductive cells (like all human body cells) have 23 pairs of chromosomes. In each pair there is one chromosome that was originally inherited from the mother and there is also one that was inherited from the father. One chromosome from each pair.

As chromosomes are paired, so are genes.

Reproduction:

During sexual reproduction the sperm and the egg cells ( with 23 chromosomes each) join to form a new cell with the full 46 chromosomes. The cells contain DNA from each parent which is combined in this process. The 46 chromosomes contain different pieces of variation and everytime this process occurs, different variations will be given.


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