Cell - The Structure and Functions

The cell wall lies outside the cell membrane; cell wall is freely permeable and non-living, while cell membrane is selectively permeable and living

Step 1: In a plant cell, starting from the outside, the CELL WALL is the outermost boundary. Step 2: Just inside the cell wall lies the CELL MEMBRANE (plasma membrane). Step 3: The cell wall is made of CELLULOSE, is NON-LIVING, and is FREELY PERMEABLE (allows all dissolved substances to pass). Step 4: The cell membrane is a LIVING structure, present in both plant and animal cells, and is SELECTIVELY PERMEABLE (controls what enters and exits). Step 5: These are TWO SEPARATE structures with different compositions and functions. Option A reverses their positions. Option C reverses their positions

Chromosomes contain genes, and genes are responsible for transmitting characteristics from parents to offspring

Step 1: Inside the nucleus, there is nucleoplasm (the fluid inside the nucleus). Step 2: Within the nucleoplasm, there are thread-like structures called CHROMOSOMES. Step 3: Each chromosome contains smaller units called GENES. Step 4: These GENES carry the genetic information — they are responsible for transmitting characteristics (like eye colour, height, skin colour) from PARENTS to their OFFSPRING. Step 5: The hierarchy is: Nucleus → Nucleoplasm → Chromosomes → Genes → Traits. Option A is wrong because nucleoli are separate structures in the nucleoplasm and do NOT contain genes. Option C is

20 chromosomes, because the number of chromosomes is definite and the same in every cell of the same species

Step 1: The chapter clearly states that 'the number of chromosomes is definite in each species'. Step 2: For example, EVERY cell in the human body (whether it is a skin cell, muscle cell, or nerve cell) has 46 chromosomes. Step 3: Similarly, EVERY cell in a pea plant has 14 chromosomes. Step 4: This is a fundamental biological rule — the chromosome number is SPECIES-SPECIFIC and CONSTANT across all body cells of the same organism. Step 5: Therefore, if one body cell of the new species has 20 chromosomes, every other body cell of that organism will ALSO have 20 chromosomes. Option A is wrong —

Chloroplasts (green, photosynthesis), Chromoplasts (yellow/red, attract insects for pollination), Leukoplasts (colourless, store starch/fats/proteins)

Step 1: CHLOROPLASTS are GREEN plastids that contain the green pigment chlorophyll. Their function is to TRAP SOLAR ENERGY for PHOTOSYNTHESIS — making food for the plant. Step 2: CHROMOPLASTS contain YELLOW and RED pigments. They give varied colours to FLOWERS and FRUITS. In petals, they ATTRACT INSECTS for pollination. Step 3: LEUKOPLASTS are COLOURLESS (leuco = white/colourless) plastids found mainly in SEEDS. Their function is to STORE starch, fats, and proteins. Step 4: All three types are found ONLY in plant cells — animal cells do NOT have plastids. Step 5: Options B, C, and D all mix up