Answer:
1. Chromatin condense into chromosomes.
4. Homologous chromosomes pair up (formation of tetrads).
5. Homologous chromosomes separate and move to poles.
2. Sister chromatids separate.
3. Chromosomes unravel in to chromatin.
Explanation:
This question portrays the process of meiosis in a cell. The ordered sequence of events in the options are:
1. Chromatin condense into chromosomes - This process occurs in the Prophase stage. Prior to the cell division, the nuclear material is found as Chromatin material. This Chromatin material then undergoes condensation to form visible chromosomes.
4. Homologous chromosomes pair up (formation of tetrads) - This process also occurs during the Prophase stage of meiosis I. In this stage, homologous chromosomes (similar but non-identical chromosomes received from each parent) are paired up side by side to form a structure known as TETRAD or BIVALENT.
5. Homologous chromosomes separate and move to poles - This process characterizes the Anaphase stage of meiosis I. Homologous chromosomes are pulled apart to opposite poles of the cell by spindle microtubules.
2. Sister chromatids separate - After meiosis I, meiosis II involving sister chromatids instead of homologous chromosomes follows. In the Anaphase stage of meiosis II specifically, sister chromatids are pulled apart towards opposite poles of the cell.
3. Chromosomes unravel in to chromatin - After the whole division process i.e. karyokinesis (division of the nuclear material), the chromosomes begin to unravel to form the CHROMATIN threads once again. This process occurs in the Telophase stage of meiosis.
Answer:
The rift valley formed when the crust pulled apart.
Explanation:
The statement that best describes how the Great Rift Valley in Africa formed is that they formed when the crust pulled apart.
- This is geologically known as divergence.
- The Arabian plate and the Nubian/Somali plate are divergent plates.
- They are currently moving apart and away from each other.
- This creates a crack on the earth which is what formed the rift valley in Africa.
- Along such margins, earthquake activities are prominent.
Answer:
The correct order of events is:
C) Nicotine binds to the transmembrane protein that normally binds the neurotransmitter acetylcholine.
A) The acetylcholine receptor is an ion channel, and when a ligand binds, the ion channel opens.
B) An influx of ions carries the signal to the reward areas of the brain.
D) The signal causes release of dopamine in the brain, which causes good feelings.
E) Nicotine is quickly eliminated from the body (causing cravings for more cigarettes to produce good feelings).
Explanation:
Nicotine acts on acetyl cholinergic receptors that are located in membranes of the midbrain neurons. Nicotine can activate those receptors or block them more efficiently than acetylcholine. Stimulation of nicotinic receptors leads to an increase in ions flow that reaches the brain and causes dopamine release in the nucleus accumbens through axonal prolongations of the dopaminergic pathway. This response is responsible for the smoker´s recompense sensation.
The dopaminergic pathway is the most important way in the process of nicotine dependence and addiction to the drug.
Answer:
The coastal upwelling and changes in wind and water circulation patterns is the main natural cause of dead zones.
Fertilizers cause hypoxia due to the over growth of algae on the surface of water bodies.
Explanation:
Coastal upwelling is the cause of dead zones in which water that is present in depth comes to the surface of ocean due to the movement of water because of wind. Fertilizers cause hypoxia due to the over growth of algae on the surface of water bodies. The fertilizers increases the algal growth by providing nutrients necessary for its growth. This over growth decreases oxygen concentration in water and affect marine organisms.
Answer:
to stop animals from eating plants
Explanation:
the thorns and spines help protect the plant for example if we touch the plant it hurts same goes with animals
