The human reproductive system is different in males and females. When a sperm and egg join, the egg is fertilised and a baby starts to develop. Its mother provides all a baby’s needs until it is born.Fertilisation happens when an egg cell meets with a sperm cell and joins with it. The fertilised egg divides to form a ball of cells called an embryo. The embryo attaches to the lining of the uterus. It begins to develop into a fetus and finally into a baby.The mother’s lifestyle can affect the developing fetus. For example, smoking reduces the amount of oxygen in the bloodstream. This can lead to low birth weight and premature birth (when a baby is born too soon). Drinking alcohol during pregnancy can harm the developing baby’s nervous system, especially its brain.
Birth
It takes about 40 weeks for a baby to develop in the uterus. This time is called gestation. After this, the baby is ready to be born. The cervix relaxes and muscles in the wall of the uterus contract. Waves of muscle contraction push the baby out of the mother's body through the vagina.
90 mammal species become extinct in the period 1901-2000 than became extinct in the period 1801-1900.
Extinction is a situation in which something no longer exists. Their can be many reasons associated like species have been hunted to the point of extinction, scarcity of food or natural disasters.
Their are two main types of extinction firstly Mass extinction that has occurred only five times in history. The other is Background extinctions which occurs over longer period of time and are considered important in natural extinction rate.
To learn more about Extinction , here
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Mitotic spindles are microtubule-based structures that separate chromosomes during mitosis. So the cell would lack structure.
Answer:
100% or 1
Explanation:
This question involves a gene coding for fur color in bears. According to the question, black fur allele (B) is dominant over the brown fur allele (b). This means that a bear heterozygous for fur color (Bb) will be phenotypically black.
In this question, a black father bear (genotype BB) and a brown mother bear (genotype bb) were crossed, the baby bears will all have a genotype Bb (see punnet square in the attached image). Since all the offsprings of this cross have genotype Bb, this means that 100% will have black fur.
