Live practice

\(n=\frac{c}{v}\), therefore

No. A resemblance correlation alone gives no controlled crosses, parental genotypes or offspring ratios. Both a dominant allele shared by parents and a recessive allele inherited from carrier/affected parents can produce the observation. A larger pedigree with known relationships and segregation patterns is required.

Pollination is transfer of pollen grains from anther to stigma and may occur by wind, water or animals. Fertilisation occurs later, after pollen germination: a male gamete travels through the pollen tube and fuses with the egg in an ovule to form a zygote. Pollination is transfer; fertilisation is gamete fusion.

Auxin promotes cell elongation, particularly in shoots. Gibberellins and cytokinins are also growth-promoting hormones.

Most food molecules are too large and insoluble to cross the intestinal wall. Digestive enzymes catalyse hydrolysis: carbohydrates to simple sugars, proteins to amino acids and fats to fatty acids plus glycerol. These small soluble products can be absorbed and assimilated.

During the change, ethanol gains oxygen and loses hydrogen:

Gain of oxygen or loss of hydrogen is oxidation. Acidified potassium dichromate or alkaline potassium permanganate supplies the oxygen.

Na has one valence electron, O has six, and Mg has two. Two sodium atoms each transfer one electron to an oxygen atom:

Thus \(\ce{Na2O}\) contains \(2\ce{Na+}\) and \(\ce{O^{2-}}\).

One magnesium atom transfers both valence electrons to oxygen:

Thus \(\ce{MgO}\) contains \(\ce{Mg^{2+}}\) and \(\ce{O^{2-}}\). In each case the ions acquire stable noble-gas configurations.

Dilution of a concentrated acid releases a large amount of heat. When acid is added slowly to a larger volume of water with continuous stirring, the water absorbs and disperses the heat safely.

If a small quantity of water is poured into concentrated acid, that water can heat suddenly, boil and splash corrosive acid out of the container. Therefore acid is always added to water, preferably along the side of the vessel.

Principle. Insert each fixed x. Every point retains \(A=3.0\,\mathrm{cm}\) and ω=36 rad s⁻¹; position changes only phase.

All are sinusoidal with frequency 36/(2π)=5.73 Hz and amplitude \(3.0\,\mathrm{cm}\). Their phase increases by kΔx, so different points reach corresponding states at different times.

Principle. The supports prevent the free thermal contraction α|ΔT|. The same magnitude becomes tensile mechanical strain, giving stress Yα|ΔT|.