Inheritance and Evolution Flashcards
What are Alleles
Alleles are pairs of genes that are inherited – one from each parent
Genetic Variation only=
Eye colour
Blood Group
Attached Ear Lobes
Animals fur colour
Environmental variation only=
Tatoos
Scars
Language Spoken
Colour of hydrangea flower - blue in acid, pink in alkaline
Genetic and environmental variation n=
Height
Weight
Humans hair colour -
can lighten in summer or can be dyed
Size of plant
Explain how alleles form:
The sperm and the ovum (egg cell) each carry half of the DNA from the parent. These join together during fertilisation to form a new organism, with approximately half of the DNA from each parent. So there are almost always two copies of each gene. Pairs of genes for a characteristic are called alleles. Therefore there are alleles for almost every one of your characteristics
What is the difference between a genotype and a phenotype?
Genotype= The combination of alleles in an organism. Genotypes are often written as pairs of letters - one for each gene.
Phenotype= The appearance of the organism’s genotype. Phenotypes are often written as words.
What is a dominant allele?
An allele that always expresses itself whether it is partnered by a recessive allele or by another like itself.
heterozygous=
This describes a genotype in which the two alleles for a particular characteristic are different
homozygous=
This describes a genotype in which the two alleles for the characteristic are identical.
What is a recessive allele?
Alternative form of a gene that is expressed only if a dominant allele of that gene is not present. An organism must have two copies of a recessive allele for that allele to be expressed.
Name 4 adaptations of plants (in rainforests):
Many trees in the rainforest have tall, thin trunks to allow them to quickly grow towards the light.
Lots of plants have smooth trunks and stems, and drip tips to their leaves to allow water to run off without damaging the plant.
Some trees have large buttress roots which anchor them into the ground meaning they can grow very tall.
Other plants called epiphytes grow on the higher branches of trees and get their water and nutrients from the air, not their roots. They grow here to absorb more light for photosynthesis.
Name 6 adaptations for a cactus in the desert:
Stems that can store water.
Widespread or very deep root systems that can collect water from a large area or from very deep underground.
Spines which prevent the plant being eaten.
The spines are modified leaves. These minimise the surface area and so reduce water loss.
Very thick, waxy cuticle to reduce water loss.
Reduced number of pores called stomata to reduce water loss.
Polar bears hibernate through the most severe months and have:
Thick white fur for camouflage. Greasy fur to remove water quickly after swimming. A thick layer of fat to keep warm. Sharp teeth and claws for hunting. Large feet to spread their weight on the
Endangered species could be helped by conservation measures such as:
education programmes
captive breeding programmes
legal protection and protection of their habitats
making artificial ecosystems for them to live in
Name 3 reasons why We should conserve endangered species:
maintains the future possibility that plant species might be identified for medicines
keeps damage to food chains and food webs to a minimum
protects our future food supply
