In a monohybrid cross when $F‌‌_1$ is crossed with homozygous dominant parent then which type of offsprings will obtain

The leaf colour of certain plants is controlled by one gene. For that gene, the allele $G =$ orange and $g =$ green. You have a plant with orange leaves, but do not know whether that plant's genotype is $GG$ or $Gg.$

If you cross your unknown plant with one of the plants whose genotype is listed below, you will be able to determine your unknown's genotype. With which plant would you cross it?

The alleles are

Find out the percentage of dominant phenotype in cross between $P_p$ and $P_p$. $P-$dominant, $p-$recessive

In a monohybrid cross of plants with red and white flowered plants, Mendel got only red flowered plants. On self-pollinating these $F_1$ plants got both red and white flowered plants in $3:1$ ratio. Explain the basis of using $RR$ and $rr$  symbols to represent the geno type of plants of parental generation.