• Centromere: Holds the 2 sister chromatids together.
• Telomere: Protects the chromosome from damage.
• Nucleosome: Basic unit of chromatin.

Centromere and telomere are responsible for the segregation of chromosomes during cell division and for protecting the chromosomes from damage, respectively.

Chemical Components Synthesized in Interphase:

1. G1 phase (Gap 1): The cell synthesizes proteins and enzymes necessary for growth and organelle duplication, and prepares for DNA replication.
2. S phase (Synthesis): DNA replication occurs, leading to the synthesis of identical copies of DNA (chromatids).
3. G2 phase (Gap 2): The cell synthesizes proteins, especially microtubules and other components required for mitosis, and checks for DNA replication errors.

Consequences of Loss of Normal Control:

1. Uncontrolled cell division: If control is lost at cell cycle checkpoints (G1, G2, or metaphase), cells may divide uncontrollably, leading to cancer.
2. DNA damage propagation: Without proper control, damaged or incomplete DNA may be replicated and passed on to daughter cells, leading to mutations and genetic disorders.

OR

Alternation of generation

The two changes that happen in opposite natures in prophase and telophase:

• Chromosomes condense in prophase and decondense in telophase.
• The nuclear envelope breaks down in prophase and reforms in telophase.

The genotypes of pea plants having yellow and round seeds produced in the F₂ generation of Mendel's dihybrid cross are:

• YYRR
• YyRR
• YYRr
• YyRr

Law of Independent Assortment: Two or more pairs of contrasting factors or genes for two or more characters of an organism segregate independently during gamete formation appearing in all possible combinations in the gametes.

Seven contrasting characters of the pea plant were selected by Mendel.

Three reasons behind his success in performing these experiments:

1. Mendel chose the pea plant because it is a self-pollinating plant. This means that he could control the pollination process and ensure that the parents of the next generation were true-breeding for the traits he was studying.
2. The pea plant has easily observable traits. This made it easy for Mendel to track the inheritance of the traits from one generation to the next.
3. The pea plant has a relatively short generation time. This allowed Mendel to conduct multiple generations of experiments in a relatively short period of time.

(d) It is an induced movement of curvature controlled by the direction of the stimulus.

(b) Adrenaline decreases cardiac output

(c) 12 pairs

(d) Chromosome and Spindle fibre are not formed

(c) It produces haploid gamete containing hereditary variations

(b) Fragmentation – Spirogyra

(c) Colour of the cotyledon – Yellow

(a) One type

(d) rrYY and rrYy