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Question 1

Identify and describe the events of the cell cycle (animal and plant cell).

Answer 1

-Cell cycle is the serious events that cells go through as they grow and divide.

3 phases of interphase
G1: cell increases in size and synthesizes new proteins and organelles.
S: proteins associated with DNA are also synthesized.
G2: Organelles and molecules required for cell division are produced.

4 phases of mitosis
Prophase: chromosomes become visible and centrioles take up position on the opposite sides of the nucleus
Metaphase: chromosomes line up across the center of the cell
Anaphase: chromosome move until they form 3 groups near the poles of spindle.
Telophase: nuclear envelope reforms around each group of chromosomes and mitosis are complete but cytokinesis is not.

Question 2

What are chromosomes and why is it so important to maintain the number of chromosomes during cell division?

Answer 2

Chromosomes are made up of DNA and proteins and are only visible during cell division.

If there are too many or too few chromosomes, inside a cell, then there will be a corresponding increase or decrease in the number of proteins that are made. This probably causes cell stress and leads to cellular damage.

Question 3

How is cell division controlled (how is it regulated)?

Answer 3

Controlled by cyclins, internal regulators and external regulators.

Question 4

What is the link between mitosis and cancer?

Answer 4

Cancer is essentially a disease of mitosis. The normal ‘checkpoints’ regulating mitosis are ignored or overridden by the cancer cell. Cancer begins when a single cell is transformed or converted from a normal cell to a cancer cell.

Question 5

Describe, in detail, the stages of meiosis and cytokinesis.

Answer 5

Mitosis
The process of reduction division in which the number of chromosomes per cell is cut in half chromosomes in a diploid cell.
Process made up of: Interphase + Meiosis l + Meiosis ll

Cytokinesis
Cytokinesis in plants is different with the development of the cell plate which becomes a separating membrane and eventually a cell wall
This is M phase

Question 6

Explain why it is important to reduce the number of chromosomes.

Answer 6

Because meiosis creates cells that are destined to become gametes, this reduction in chromosome number is critical. Without it, the union of two gametes during fertilization would result in offspring with twice the normal number of chromosomes.

Question 7

Describe crossing-over and why it is important.

Answer 7

Crossing over is a cellular process that happens during meiosis when chromosomes of the same type are lined up.

Homologous chromosomes exchange alleles/genes to produce new chromosomes.

Question 8

Describe nondisjunction in human chromosomes and the conditions that it may cause (Down’s syndrome, Turner syndrome etc.)

Answer 8

An individual may be born with three copies of a chromosome. This is called trisomy. The most common form of trisomy is Downs Syndrome. Downs Syndrome results from an extra copy of chromosome 21. It reduces mild to severe mental retardation and increases the susceptibility to many diseases and higher frequency of some birth defects.

Question 9

Be able to identify a normal karyotype vs. an abnormal one.

Question 10

What are the main scientific discoveries that led to the knowledge of structure, function and replications of DNA. (Griffith, Avery, Hershey-Chase)

Answer 10

Griffith
Genetic information could be transferred from one bacteria to another, he called this process of transformation.

Avery
The DNA stores and transmits the genetic information from generation of an organism to the next.

Hershey-Chase
DNA is genetic material.

Question 11

Describe the Watson and Crick double helix model of DNA

Answer 11

Twisted ladder

Held together with hydrogen bonds but only between certain NB

The hydrogen bonds are weak but just strong enough to hold the ladder together

This rule is called base pairing

Question 12

Explain DNA replication. (Don’t forget about Chargaff’s rule of base pairing)

Answer 12

The two strands have separated allowing two replication forks to form. As each new strand is formed, new bases are added following the rules of base pairing which is the principle explained by Chargaff’s rules: adenine (A) always bonds with thymine (T) and cytosine (C) always bonds with guanine (G).

Question 13

Compare and contrast the structure of DNA and tRNA, mRNA and rRNA and explain their role in protein synthesis.

Answer 13

DNA and tRNA
DNA are wrapped around histones but tRNA has a specific amino acid attached.

mRNA and rRNA
mRNA molecules carry the coding sequences for protein synthesis and are called transcripts but rRNA molecules form the core of a cell’s ribosomes.

Question 14

Explain the process of transcription and translation..

Answer 14

Transcription
The process in which the DNA sequence of a gene is transcribed to make an RNA molecule.

Translation
Take place in the ribosome.
During translation, the cell uses information from mRNA to produce proteins.

Question 15

Explain what is a gene mutation and how it can protein synthesis.

Answer 15

Gene mutation changes in a single gene
The ribosome won’t read the correct amino acid.

Question 16

Explain how protein synthesis comes into play in cystic fibrosis and sickle cell anemia.

Answer 16

When protein isn’t present in the membrane as it should be, then it cannot be transported to the cell membrane. So the cells in the person’s airway and lung are unable to transport chloride ions as long as a result the airways become clogged with thick mucus. Therefore, their lungs don’t function properly. Just because of that missing amino acid.

Question 17

Describe the life and work of Gregor Mendel and how his studies led to the beginning of the understanding of the inheritance of genes.

Answer 17

Mendel was a monk who studied science and mathematics. He spent 14 years teaching high school and working in a monastery where he was in charge of the garden.

The crux of his works consisted of the study of pea plants.

He concluded that Biological inheritance is determined by factors that are passed from one generation to the next, and the Principle of Dominance states that some alleles are dominant and others are recessive.

Question 18

Understand and describe independent assortment, complete/incomplete dominance, codominance, multiple alleles and polygenic traits.

Answer 18

Independent assortment
One allele is not completely dominant over another
The heterozygous phenotypes are somewhere in between the two homozygous phenotypes
E.g. flower colour in four o’clock plants

Codominance
Both allele contribute to the phenotype of the organism
E.g. black and white feather colour in certain varieties of chickens

Multiple alleles
Genes have more than two alleles
E.g. blood types in humans and eye colour in humans

Polygenic traits
Two or more genes control a trait
E.g. skin colour in humans
Predict the outcome of monohybrid and dihybrid crosses using genotype and phenotype ratios.

Question 19

Know what the theory of evolution is.

Answer 19

A collection of scientific facts, observations, and hypotheses which states that modern organisms have descended from ancient organisms.

Question 20

Describe Darwin’s voyage and what he observed.

Answer 20

He travelled all over the world, to places that people had never been before. Then he saw a whole bunch of different animals, plants and fossils, he also collected samples from all over.

He observed the patterns of diversity in which plants and animals were well suited to whatever environment they lived in.

Question 21

Discuss that ideas and scientists who shaped Darwin’s thinking (Hutton, Lyell, Lamarck and Malthus)

Answer 21

Hutton
Proposed that the earth is shaped by geological forces that took place over extremely long periods of time.
Estimated that the earth is millions, not thousands of years old.

Lyell
Explains that processes occurring now have shaped Earth’s geological features over long period of time.

Lamarck
Published his hypotheses of the inheritance of acquired traits.
Explains how organism changes over time.

Malthus
Predicted that the human population will grow faster than the space and food supplies needed to sustain it.

Question 22

Discuss the weaknesses of Darwin’s theory.

Answer 22

Scientific advances in many fields of biology have confirmed and expanded most of Darwin’s hypothesis but the evolutionary theory continues to change as new data are gathered and new ways of thinking arise.

Still much debate on how new species arise and why species become extinct.

There is also uncertainty about how life began.

Question 23

Describe and give an example of homeostasis.

Answer 23

The process by which organisms keep internal conditions relatively constant despite changes in the external environments.

Non-living examples: Heating system of a house is controlled by feedback inhibition.

Living examples: Body temperature control in humans

Question 24

Explain feedback inhibition.

Answer 24

Process in which a stimulus produces a response that opposes the original stimulus.

Question 25

Explain the structure of a neuron.

Question 26

Describe the functions of the different types of neurons. (sensory, motor and interneurons)

Answer 26

Sensory neuron: senses something external and internal

Motor neuron: carries the impulse e from the brain or spinal cord to the body

Interneuron: neurons inside the brain and spinal cord that bridge the sensory neuron with the motor neurons, or communicates with other neurons in the brain, and integrates the message once received from the sensory neuron.

Question 27

Describe the transmission of a nerve impulse.

Answer 27

The transmission of a nerve impulse along a neuron from one end to the other occurs as a result of electrical changes across the membrane of the neuron.

Question 28

Describe the basic structure of the central nervous system (this includes the cerebrum, cerebellum, medulla, and spinal cord).

Answer 28

Cerebrum
- Largest part of the brain.
- Responsible for the voluntary activities of the body.
- Divided into two hemispheres right and left that are joined by the corpus callosum.
- Made up of 2 layers, which is cerebral cortex(grey matter) and inner layer(white matter).

Cerebellum
- Second largest part of the brain.
- The center of coordination and balance.
- Makes sure that the muscles work together.

Medulla
- Controls the flow of information between the brain and the rest of the body.
- Control blood pressure, heart rate, breathing

Spinal cord
- Is the communication link between the brain and the rest of the body.
- 31 pairs of spinal nerves run out of the spinal cord.

Question 29

Describe the basic functions of the peripheral nervous system (this includes the somatic and autonomic nervous system.

Answer 29

PNS divided into two divisions
- Sensory division: transmits impulses to the CNS, and tells us about our environment.
- Motor division: transmits impulses from the CNS to muscles or glands, and helps us react to the environment.

Motor division divided into 2 system
- Somatic nervous system: control of activities that are under conscious control like movement.
- Autonomic nervous system: regulates activities are automatic or involuntary control.

Question 30

Describe the general structure and function of the eye. (lens, iris, cornea, retina, vitreous fluid, choroid, fovea, rods, cones, and blind spot).

Answer 30

Lens: Change its shape to help you adjust your eyes to focus on near or distant objects.

Iris: Disk-like structure, the coloured part of the eye.

Cornea: Light enters. Helps focus the light.

Retina: Inner layer of eye that contains photoreceptors, which convert light energy into nerve impulses.

Vitreous fluid:

Choroid: Middle layer of eye that is rich in blood vessels.

Fovea:

Rods: Extremely sensitive to light but do not distinguish colours.

Cones: Less sensitive to light but distinguish colours.

Blind spot: Provides vision, ​​to see everything that is happening around us.

Question 31

Describe the general structure and function of the ear. (tympanic membrane, ossicles (hammer, anvil, stirrup), eustachian tube, semicircular canals, cochlea.

Answer 31

Tympanum (ear drum): the vibrations cause the tympanum to vibrate.

Hammer, Anvil, Stirrup: pick up the vibration.

Eustachian tube:

Semicircular canals: 3 tiny canals and the two tiny sacs behind them monitor the position of your body and help us maintain balance.

Cochlea: lined with tiny hair cells that are pushed back and forth by these pressure waves.

Question 32

Describe how certain drugs can affect the nervous system.

Answer 32

Simulants
- Increase the action regulated by the nervous system (increase heart rate, blood pressure, breathing rate)
- Increase the release of certain neurotransmitters in some synapses in the brain
- E.g. Cocaine, Nicotine, Caffeine, (Marijuana)

Depressant
- Decrease the action regulated by the nervous system (decrease heart rate, blood pressure, breathing rate)
- Decrease the release of some neurotransmitters, or increase the release of inhibitory neurotransmitters
- E.g. Alcohol, Opiates, (Marijuana)

Question 33

Identify the location and function of the endocrine glands and their hormones. (only the ones that we went over in class)

Question 34

Describe the relationship between hormones and target cells.

Answer 34

Hormones bind to specific receptors on specific cells, but target cells have those specific receptors, and each hormone has target cells.

Question 35

Compare and contrast steroid and non-steroid hormones and how they affect target cells.

Answer 35

Steroid hormones
- Made up of lipids so they can cross the cell membrane and the nuclear membrane.

Non-steroid hormones
- Made of proteins, small peptides and modified amino acids.

Question 36

Know the structures and functions of the male and female reproductive systems.

Question 37

Describe the structure of sperm.

Question 38

Describe the following steps of fertilization: early development, implantation, gastrulation, neurulation.

Answer 38

Early development:
Implantation: At day 7, the blastocyst reaches the uterus and implants into the uterine wall
Gastrulation: In week 3, the inner cell mass organizes itself into ectoderm, mesoderm, endoderm.
Neurulation: Shortly after gastrulation, around weeks 3-6, a block of mesodermal tissue differentiates into the notochord

Question 39

Explain what the placenta is and how the exchange of nutrients/wastes happens between the embryo/fetus and the mother.

Answer 39

The placenta is the embryo’s organ of respiration, nourishment, and excretion. The umbilical cord connects the fetus to the placenta.

The mother’s and embryo’s blood do not mix but flow past each other along the border of the placenta. Materials are diffused from the embryo to the mother and back via the chorionic villi.

Question 40

Know what happens in the latter stages of pregnancy (fetal development)

Answer 40

All of these stages have occurred by week 8 of development, in which the embryo is now called a fetus.
By 3 months, most main organs have formed, including the muscular system.
In months 4, 5, and 6 organs grow and become more complex. The fetal heartbeat can be heard, cartilage is replaced by bone and hair forms.
Lungs and nervous systems take the longest to fully develop.
The average gestation period for humans is 9 months