If the diploid chromosome number of a young horse is 64, what will be the number in its bone cells after mitosis as it grows?

43. If the diploid chromosome number of a young horse is 64, what will be the number in its bone cells after mitosis as it grows?

Step 1: Understand mitosis. Mitosis is a type of cell division that produces two daughter cells genetically identical to the parent cell. This process is responsible for growth and repair in multicellular organisms.

Step 2: Determine the chromosome number after mitosis. Since mitosis produces cells with the same chromosome number as the parent cell, the bone cells (somatic cells) of the horse will maintain the diploid chromosome number.

The diploid chromosome number is given as 64. Therefore, the bone cells after mitosis will also have 64 chromosomes.

The final answer is $\boxed{C. 64}$.

44. 2 ml of a food solution was placed in a test tube, 1ml of NaOH (Sodium hydroxide) and 4 drops of CuSO$_4$ (Copper II Sulphate) were added respectively, into the test tube and shaken. The appearance of a purple colour indicated the presence of which class of food?

Step 1: Identify the reagents used. The reagents used are Sodium hydroxide (NaOH) and Copper (II) Sulphate (CuSO$_4$).

Step 2: Identify the test performed. This combination of reagents (NaOH and CuSO$_4$) is characteristic of the Biuret test.

Step 3: Interpret the result of the test. The Biuret test is used to detect the presence of proteins. A positive result is indicated by a purple or violet color, which signifies the presence of peptide bonds.

The final answer is $\boxed{D. Protein}$.