6 or 7
A child's 20 baby teeth, which often come in by age 3, usually fall out in the same order they came in. That means the lower center teeth (lower center incisors) are usually the first to go, around age 6 or 7. The top center pair is next.
Answer;
D. controlled
An experiment in which only one variable is changed is a controlled experiment.
Explanation;
-A control experiment is an experiment where the researcher only changes one variable at a time in order to isolate the results.
In a controlled experiment, most conditions are constrained so that they do not change. One or two other conditions are then changed and measured by the experimenter. These are known as the independent variables.
For example; An experiment where all subjects involved in the experiment are treated exactly the same except for one deviation.
Answer:
25% of the offsprings will be BBCC
Explanation:
This is a typical dihybrid cross involving two distinct genes. One coding for fur colour and the other for claw sharpness. The allele for brown fur (B) is dominant over the allele for black fur (b) in the first gene while the allele for sharp claws (C) is dominant over the allele for dull claws (c) in the second gene.
In a cross between parents with genotypes: BbCc x BBCC , each parent will produce four possible allelic combinations of gametes as follows:
BbCc: BC, Bc, bC, bc
BBCC: BC, BC, BC, BC
Using these gametes in a punnet square (see attached image), 16 possible offsprings will be produced with four distinct genotypes:
BBCC (4)
BBCc (4)
BbCC (4)
BbCc (4)
According to the question, an offspring that is homozygous dominant for both traits will possess a genotype: BBCC
N.B: Homozygous dominant means contains same alleles for the dominant trait.
Hence, offsprings with genotype, BBCC, from this cross are expected to be 4 out of the 16 possible offsprings. Hence, the percentage is 4/16 × 100 = 25%.