• Cortex: Correct. It is a thick, specialized form of peptidoglycan.
• Core: Correct. It contains the bacterial chromosome/DNA and abundant calcium dipicolinate. This helps keep the core dehydrated and contributes to heat resistance.
• Spore coat: Broadly acceptable for basic exam purposes, but “keratin-like protein” is imprecise. The spore coat is better described as a thick, multilayered proteinaceous protective coat, composed of spore-coat proteins. It is not literally keratin.
• Order: The simplified outer-to-inner order, spore coat → cortex → core, is correct. However, a fuller description includes an outer membrane, germ cell wall, and inner membrane between/around these structures. Some organisms also have an exosporium outside the coat. The NCBI endospore micrograph description illustrates these additional layers.

Outside to inside: spore coat (proteinaceous) → cortex (specialized peptidoglycan) → core (dehydrated cytoplasm containing DNA, ribosomes, enzymes, and calcium dipicolinate).