Which of the following is an example of mutualism?
a) a rabbit population is the main source of food for a certain fox population
b) ticks can attach and live on the blood of bison
c) in their attempt to obtain nectar from blooms, bees pollinate a population of flowers
d) birds feed off the flies that swarm around buffalo

Answer is option D - (1) nucleolus, (2) vacuole.

Explanation:

The plant cells are eukaryotic cells that contain an organized nucleus and membrane-bound organelles. The basic structures found in a plant cell are cell wall, cell membrane, cytoplasm, nucleus, nucleolus, mitochondria, ribosomes, chloroplasts, vacuole, endoplasmic reticulum, Golgi apparatus, peroxisomes, etc.

The outermost covering structure of plant cells called cell wall is mainly made up of cellulose and also contains hemicellulose, pectin, and lignins. It provides strength and support to the plant cell and also helps to maintain the cell turgidity. The semi-permeable cell membrane (double phospholipid layer) which surrounds the cell, controls the movement of certain substances in and out of the cell.

The fluid inside the cells called cytosol (made of water, dissolved nutrients, and salts) and structures called organelles except the nucleus constitutes the cytoplasm (a jelly-like material). The network of filaments and tubules inside the cytoplasm is known as cytoskeleton and it provides strength, cell shape, and anchors organelles within the cell.

The organized nucleus contains genetic material (DNA) and controls the cell’s activities including growth and division of the cell. Inside the nucleus, a structure called nucleolus is present. A large central vacuole present inside the cell is filled with fluid, ions, and other molecules. It maintains the turgor pressure (inside pressure exerted by the cell contents against the cell wall) and supports the plant and prevents it from wilting.

The oval-shaped chloroplast contains chlorophyll (a green pigment) and performs photosynthesis by absorbing light energy. The organelle called mitochondria performs cellular respiration and releases energy for the normal functioning of the cell.

Proteins synthesis takes place in ribosomes and they are modified in the endoplasmic reticulum. The proteins are then transferred to the Golgi apparatus, where they are folded, sorted, and packaged into vesicles before transportation.