State whether the following statements are true or false. If false write in the correct answer. a) Fertilisation of the egg occurs in the uterus b) The fertilised egg cell contains half the normal number of chromosomes c) The morula is a hollow ball of cells d) The mixing of the blood of the mother and foetus allows nutrients and oxygen to transfer easily to the foetus e) The morula implants in the wall of the uterus f) The placenta is the organ that supplies the foetus with oxygen and nutrients g) Colostrum is the first milk h) Young animals often have to be given calcium supplements because milk contains very little calcium

Fertilisation is the union of an egg (ovum) and a sperm to form a zygote, which is the first step in the development of a new individual. In most animals, fertilisation occurs outside the female's body (external fertilisation), as seen in many fish and amphibians, or inside (internal fertilisation), which is common among mammals, reptiles, and birds. An intriguing fact is that fertilisation in mammals typically happens in the fallopian tubes, not the uterus as sometimes misconceived.

This process is critical as it restores the normal number of chromosomes in the zygote. Each parent contributes half, resulting in a complete set within the fertilised egg. Misunderstanding the location and process of fertilisation can lead to confusion in studying animal reproductive physiology, which is why it is important to acknowledge the actual site and mechanism of fertilisation.

Embryonic development in animals follows a fascinating journey from a single cell to a complex organism. This process includes several stages, beginning with the fertilised egg, which is called a zygote. The zygote then undergoes cell division, or mitosis, forming a solid ball of cells known as a 'morula'.

As the morula continues to divide, it develops into a 'blastocyst', a hollow structure, which is the stage that actually implants into the uterus wall, contributing to a common misstatement about the morula doing so. Post-implantation, the embryo continues to develop, forming the different layers and structures that will become the various organs and parts of the body. Understanding the correct sequence and nature of these early developmental stages is crucial for grasping the complexity of mammalian reproduction.

The placenta is a remarkable organ exclusive to mammals, serving as a support system for the developing foetus. It allows for the transfer of oxygen and nutrients from the mother to the foetus, but contrary to some beliefs, the blood of the mother and foetus does not mix. This is an important protective feature that prevents the potential transfer of blood-borne diseases and also immunological reactions against the foetus.

The placenta also handles the removal of waste products from the foetal bloodstream. Another crucial aspect of neonatal nourishment involves colostrum, which is indeed the first milk produced by mammals postpartum. Rich in antibodies, colostrum is vital for the newborn's immune defenses. Also, milk from the mother is usually rich in calcium, vital for skeletal development, challenging the misconception that additional calcium supplementation is necessary in early life due to milk's insufficiency in this mineral.