What are the steps in oogenesis?

Oogenesis describes the production of female gametes (ova) within the ovary The process begins during foetal development, when a large number of cells (oogonia) are formed by mitosis before undergoing a period of growth These cells begin meiosis but are arrested in prophase I until puberty At puberty, some follicles continue to develop each month is response to FSH secretion These follicles complete the first meiotic division to form two cells of unequal size The cell with less cytoplasm is a polar body (which degenerates), while the larger cell forms a secondary oocyte The secondary oocyte begins the second meiotic division but is arrested in prophase II (until fertilisation) It is released from the ovary (ruptured follicle develops into corpus luteum) and, if fertilisation occurs, will complete meiosisThe second meiotic division will produce an ovum and a second polar body

What are the steps in spematogenesis?

Spermatogenesis describes the production of spermatozoa (sperm) in the seminiferous tubules of the testes The first stage of sperm production requires the division of germline epithelium by mitosis These cells (spermatogonia) then undergo a period of growth This is followed by two meiotic divisions that result in four haploid daughter cells These haploid cells then differentiate to form sperm cells The developing sperm cells are nourished throughout by the Sertoli cells

A blood clot contains a network of protein. What is the protein?

Fibrin

Outline how the liquid that flows through the proximal convoluted tubule (PCT) is produced

Unfiltered blood enters the glomerulus from the renal artery and goes through ultrafiltration. Blood passes through the basement membrane then passes on to the pct

Setae the name of the substances reabsorbed by the pct

Glucose, mineral ions, protein, and water

Discuss the benefits and dangers of immunizations against bacterial and viral infections

Immunizations can prevent global disease
They can accidentally cause mild symptoms or allergic reactions

Some but not all, substances that can be tested for in the urine of the patient. Why do some substances present in the bloodstream show up in urine samples and others do not?

Glucose present in urine can be tested for to find if a patient has diabetes
If it is present the patient has diabetes. If not, the patient is highly unlikely to have diabetes

Identify all of the cellular and molecular layers that a molecule would have to pass through in order to be ultrafiltered and then reabsorbed into the bloodstream within a single nephron

Ultrafiltration happens across the glomerulus and the bowman's capsule.
In order for this to move across the membranes above needs a hydrostatic pressure gradient and a basement membrane
The substances comes in through the afferent to the efferent to the proximal convoluted tubule to the loop of Henle to the distal convoluted tubule finally going to the collecting tubule

The proximal convoluted tubule extends from the Bowman's capsule and is where most selective reabsorption in the nephron occurs. All glucose, amino acids, vitamins and hormones are reabsorbed here, along with most (~80%) of the mineral ions and water. The proximal convoluted tubule has a microvilli cell lining to increase the surface area for the absorption of materials from the filtrate. There are also a large number of mitochondria in these cells, as reabsorption from the filtrate involves active transport. Once materials have been actively reabsorbed into the tubule cells, they can passively diffuse into the bloodstream (along the concentration gradient)Mineral ions and vitamins are actively transported via protein pumps or carrier proteins. Glucose is actively transported across the membrane in symport with sodium. Water follows the movement of the ions passively (via osmosis)

Describe the steps of blood clotting

Platelets or damaged cells release a group of proteins called clotting factors. These clotting factors are released into the plasma a wound site
Clotting factors activate the enzyme thrombin from its inactive form prothrombin
Thrombin turns the soluble plasma protein fibrinogen into its insoluble fibrous from fibren.
Fibrin binds together platelets and blood cells to form a solid plus for the wound. This plug is called a clot.

Discuss active vs passive immunity

Passive immunity involves no use of energy
Active immunity allows the cells in the body to use energy to fight antigens
Passive immunity is like that of an immunity from a vaccine
Active is like that of being exposed to a new flu virus and actively fighting it off

Outline the immune response to an antigen

T cells identify an antigen in the body
They then bring in the white blood cells and call the body into a protective mode
This protective node facilitates the growth of antibodies which are used to eradicate all of the antigens

Definitions for genetics

1. Homozygous- the same trait on both alleles
2. Phenotype- what of the possible genotypes actually appears
3. Carrier- someone who has a trait for a recessive gene that doesn't show, but can be passed on to the next generation
4. Can a mom with A blood and a Dad with B blood have children with O blood? Yes, both would have to be carriers of the O blood type
5. Can a Mom with hemophilia and a Dad that is normal have children with hemophilia? Yes they are very likely to have children with hemophilia

What percentage of values fall within 1 standard deviation of the mean? And 2?

About 68.27% of the values lie within one standard deviation of the mean. Similarly, about 95.45% of the values lie within two standard deviations of the mean.

What do error bars indicate?

Error bars indicate different things in different cases, they can range from errors in data collection to standard deviation, the can indicate room for mistakes in both directions from the current plotted point

What is the importance of standard deviation with regards to the mean?

Standard deviation is derived from the variance which involves using the mean and squaring values. Standard deviation shows which values follow the central tendencies of the data from the mean in either direction

Explain the role of auxin in phototropism

Phototropism is the growing or turning of an organism in response to a unidirectional light source
Auxins (e.g. IAA) are plant hormones that are produced by the tip of a shoot and mediate phototropism
Auxin makes cells enlarge or grow and, in the shoot, are eradicated by light
The accumulation of auxin on the shaded side of a plant causes this side only to lengthen, resulting in the shoot bending towards the light
Auxin causes cell elongation by activating proton pumps that expel H+ ions from the cytoplasm to the cell wall
The resultant decrease in pH within the cell wall causes cellulose fibres to loosen (by breaking the bonds that hold them together)
This makes the cell wall flexible and capable of stretching when water influx promotes cell turgor
Auxin can also alter gene expression to promote cell growth (via the upregulation of expansins)

Explain how water is carried by transpiration stream, including the structure of xylem vessels, transportational pull, cohesion, adhesion, and evaporation

Some of the light energy absorbed by leaves changes into heat, converting water in the spongy mesophyll into vapor
This vapor diffuses out of the stomata and is evaporated, creating a negative pressure gradient in the leaf
New water is drawn from the xylem (mass flow), which is replaced by water from the roots (enters from soil via osmosis)
The flow of water through the xylem from the roots to the leaf is called the transpiration stream
Water rises through xylem vessels because of two qualities:
Cohesion:  Water molecules are weakly attracted to each other via hydrogen bonds
Adhesion:  Water molecules form hydrogen bonds with the xylem cell wall
These properties create a suction effect (or transpiration pull) in the xylem
The xylem has a specialized structure to facilitate transpiration:
The inner lining is composed of dead cells that have fused to create a continuous tube
These cells lack a cell membrane, allowing water to enter the xylem freely
The outer layer is perforated (contains pores), allowing water to move out of the xylem into the leaves
The outer cell wall contains annular ligin rings which strengthens the xylem against the tension created by the transpiration stream

Compare growth, due to apical and lateral meristems in dicots

Apical Meristems
Occurs at the tips of roots and shoots
Responsible for primary growth
Develops into primary xylem and phloem
Produces new leaves and flowers

Lateral Meristems
Occurs at the cabium
Adds lateral growth to stem (Increase width)
Responsible for secondary growth
Produces secondary xylem and phloem
Produces bark on trees

Similarities in close they are composed of totipotent cells (Like stem cells)
and the are found in dicots

Identify and describe modifications of roots, stems, and leaves of different plants. Give one example of each.

Storage roots:  Modified roots that store water or food (e.g. carrots)
Stem tubers:  Horizontal underground stems that store carbohydrates (e.g. potato)
Bulbs:  Modified leaf bases (may be found as underground vertical shoots) that contain layers called scales (e.g. onion)

Outline the differences between monocotyledons and dicotyledons

The leaf veins of a monocotyledons have parallel venation while dicotyledons have reticulated venation. Monocotyledons have one cotyledon while dicotyledons have two. Monocotyledons have fibrous adventitious roots and dicotyledons have top roots with lateral branches. Monocotyledons have floral organs that appear in multiples of three while dicotyledons have floral organs that appear in multiples of four and five. The pollen in monocotyledons has single pores while the pollen in dicotyledons has three pores.