Animals can be classified into two main groups: vertebrates and invertebrates. The main difference between vertebrates and invertebrates is that invertebrates, like insects and flatworms, do not have a backbone or a spinal column. Examples of vertebrates include humans, birds, and snakes.
Explanation:
When you breathe in, or inhale, your diaphragm contracts and moves downward. This increases the space in your chest cavity, and your lungs expand into it. The muscles between your ribs also help enlarge the chest cavity. They contract to pull your rib cage both upward and outward when you inhale
Answer:
Genotype ratio: 1, 1:1, 1:2:1
Phenotype ratio: 1, 3:1
Explanation:
Single gene pair cross is also known as monohybrid cross. This means that only one gene usually with two alleles is observed and it express one trait.
For example, if we name the gene for a certain trait with A, the possible genotypes are AA (dominant homozygous), aa (recessive homozygous) and Aa (heterozygous). Possible crosses are:
P: AA x AA
F1 : all of them are AA
The same is with aa x aa (all of the offspring are with aa genotype)
P: AA x Aa
F1: AA Aa AA Aa (genotype ratio 1:1) (phenotype ratio 3:1)
The same genotype ratio is in aa x Aa (offspring will have aa Aa aa Aa-(genotype ratio 1:1) (phenotype ratio 1:1)
P: Aa x Aa
F1: AA Aa Aa aa (genotype ratio 1:2:1) (phenotype ratio 3:1)
P: AA x aa
F1: Aa Aa Aa Aa (1)
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