**1. Lysosomes involved in extracellular digestion are present in:**

d) All of these

**Explanation:**
Lysosomes are membrane-bound organelles found in eukaryotic cells. They contain various hydrolytic enzymes that are responsible for breaking down waste materials, cellular debris, and foreign particles. While the primary function of lysosomes is intracellular digestion, some cells also utilize lysosomes for extracellular digestion.

- **Cardiac cells:** Lysosomes in cardiac cells primarily function in intracellular digestion, breaking down waste products and recycling cellular components. However, in certain conditions like cardiac injury or stress, lysosomes can also release their contents extracellularly, leading to tissue damage and inflammation.

- **Sperm:** Lysosomes in sperm cells are involved in the process of capacitation. During capacitation, the lysosomal enzymes are released from the acrosome (a lysosome-like vesicle in the sperm head) to facilitate the penetration of the egg's protective layers during fertilization.

- **Zygote:** Lysosomes play a crucial role in the early stages of embryonic development, including the formation of the zygote. After fertilization, lysosomes are involved in the breakdown of maternal proteins and organelles, providing essential nutrients for early embryonic development.

Therefore, lysosomes are present in all of these cell types and can participate in extracellular digestion under specific circumstances.

**2. Lysosomal membrane is rich in:**

d) All of these (cardiolipin, sialic acid, sterols)

**Explanation:**
The lysosomal membrane is composed of lipids and proteins. It has a unique composition that distinguishes it from other cellular membranes. While the exact composition of the lysosomal membrane can vary among different cell types and conditions, it is known to be rich in several components, including cardiolipin, sialic acid, and sterols.

- **Cardiolipin:** Cardiolipin is a unique phospholipid found in the inner mitochondrial membrane and also in the lysosomal membrane. It contributes to the stability and integrity of the lysosomal membrane.

- **Sialic acid:** Sialic acid is a component of glycolipids and glycoproteins, which are abundant in the lysosomal membrane. Sialic acid residues on the cell surface play a role in cell-cell interactions and protection against enzymatic degradation.

- **Sterols:** Sterols, such as cholesterol, are essential components of the lysosomal membrane. They help maintain the fluidity and stability of the membrane and are involved in various cellular processes, including membrane trafficking and signaling.

In summary, the lysosomal membrane is rich in cardiolipin, sialic acid, and sterols. These components contribute to the unique properties and functions of the lysosomal membrane in maintaining the integrity of lysosomes and their role in intracellular digestion.