lll
What is Mitosis and why is it important
Mitosis is a process where a single cell divides into two identical daughter cells (cell division) and it’s important for growth, repair of worn out cells and asexual reproduction.
What is Meiosis and why is it important?
Meiosis is a process where a single cell divides twice to produce four cells containing half the original amount of chromosomes and it’s important because it keeps the number of chromosomes from doubling each generation, and it provides genetic diversity in offspring.
Disntinguish between Genetic Variation and Environmental Variation
Genetic variation refers to differences between individuals that are inherited from parents through genes and are passed from one generation to the next and Environmental variation is acquired and can change.
Define Inheritance
The passing of characteristics from parents to offspring through genes.
Why is Genetic Variation important to livign organisms
Variation makes it less likely that a change in
environmental conditions will wipe out an entire
species and .Some bacteria have become
resistant to antibiotics as a result of variation.
Define Phenotype
The physical or observable characteristics of an organism resulting from its genotype and the environment.
Define Homologous
A pair of chromosomes that are the same size and shape and carry the same genes at the same loci.
Define Alleles
Different forms of the same gene found at the same position on homologous chromosomes.
Define Homozygous
Having two identical alleles for a particular gene.
Define Mutation
A sudden change in the genetic material (DNA) of an organism.
Define Genotype
The genetic makeup of a cell or organism that determines a specific characteristic (phenotype).
Differentiate between Dominant allele and Recessive allele
A dominant allele is an allele that controls the characteristic in the phenotype when present and a reccesive allele is an allele is not expressed in the phenotype unless two copies are present.
What is Monohybrid Inheritance and explain what occurs.
Monohybrid inheritance is the inheritance of a single pair of contrasting characteristics controlled by one gene with two alleles, usually one dominant and one recessive. In monohybrid inheritance, an individual inherits one allele from each parent. If the dominant allele is present, it will be expressed in the phenotype, even if the recessive allele is also present. The recessive characteristic is only expressed when both alleles are recessive.
Explain the inheritane of sex in human beings and how it occurs.
The inheritance of sex in human beings is determined by the sex chromosomes inherited from the parents.
Humans have 23 pairs of chromosomes, one pair being the sex chromosomes. Females have two X chromosomes (XX), while males have one X and one Y chromosome (XY). During reproduction, the mother always produces eggs carrying an X chromosome, while the father produces sperm carrying either an X or a Y chromosome.
If an X-carrying sperm fertilises the egg, the child will be female (XX). If a Y-carrying sperm fertilises the egg, the child will be male (XY). Therefore, the father determines the sex of the child.
Explain the concept of genetic engineering
Genetic engineering changes the traits of one organism by inserting genetic material from a different
organism
Give two advantages of Genetic Engineering
Recombinant DNA technology is used in the manufacture of human insulin, allowing large quantities to be produced safely and cheaply for the treatment of diabetes.
Genetic engineering is applied in the production of food and medicine, such as genetically modified crops with higher yields and resistance to pests.
Give two disadvantages of Genetic Engineering
It may cause unpredictable effects on human health or the environment.
It raises ethical and moral concerns about altering the genetic makeup of organisms.
What happens during Interphase?
Each chromosome undergoes replication, making an identical copy of itself and the chromosomes are still long and thin, and not visible inside the nucleus.
What happens during Prophase?
The chromosomes coil and shorten, and become visible each chromosome is called a chromatid. There are 92 chromatids, but still 46 chromosomes. This is because they are attached at the centromere.
What happens during Metaphase?
Chromosomes line up along the center of the cell. A pair of structures called centrioles form at the poles of the cell, and produce spindle fibers which attach to the centromeres of each chromosome pair.
What happens during Anaphase?
The paired chromosomes split at the centromere and the two halves migrate along the spindle fibers to opposite sides of the cell. At the same time, the centre of the cell begins to pinch.
What hapens during Telophase?
The final stage of mitosis where the nuclear envelope reforms around the separated sets of chromosomes,
What happens during Cytokinesis?
During cytokinesis, the parent cell splits into two, and thus each daughter cell gets 46 chromosomes, the original amount.
What happens during STAGE 0 Interphase in Meiosis?
DNA replication takes place before the start of meiosis
-
SECTION A : LIVING ORGANISMS AND THE ENVIRONMENT21
-
Nutrition39
-
The Respiratory System14
-
The Circulatory & Lymphatic Systems18
-
Skeletal System10
-
Coordination and Control16
-
The Eye15
-
Reproductive System29
-
Heredity & Variation30
-
Excretion & Homeostatis13
-
Disease And Its Impact on Humans19
-
The Water Cycle & Pollution22
