Answer:
mutualism and parasitism
Examples:
mutualism: crocodiles and birds
parasitism: mosquitoes and humans
Answer:
One fertilizes the egg, and the other combines with the two polar nuclei.
Explanation:
Answer:
If the two organisms are heterozygous for the dominant trait.
Explanation:
For every trait, a diploid organism receives two forms of gene called ALLELE, from each parent. Allele is the variant form of a gene.
According to Mendel's law of dominance, for a particular trait, an allele is capable of masking the expression of another allele in a gene. The expressed allele is called the DOMINANT allele while the masked allele is called the RECESSIVE allele. Due to this, an organism can express a dominant trait even in a combined or heterozygous state i.e. different alleles.
When the two heterozygous organisms mate or are crossed, they undergo meiosis and their alleles are separated into GAMETES according to Mendel's law of segregation. For example; an organism with genotype (genetic make-up) Aa will produce gametes with A and a alleles.
Note that, a recessive trait can only be expressed in a homozygous state i.e. same allele. Hence, the two heterozygous organisms will produce gametes containing the recessive allele, which will likely combine to produce a recessive phenotype or trait.
