Chapter D

Question 1

What is the cause of evolutionary change, and what are some processes of your answer (DOVS)?

Answer 1

Evolutionary change can be credited to natural selection.

Natural selection is the removal or extinction of organisms or a species by nature or occuring naturally.

Processes of natural selection (DOVS):

• Different survival abilities: some organisms in a species have better survival skills than other typically the ones with better skills survive and the lesser falls prey to preditors and natural disasters.
• Overproduction: Over production of organisms in a species can cause for a lack of availability of necessary nutrients. This links to the last process of natural selection.
• Variation: due to meiosis all organisms are not the exact same, some may end up lacking the genetics that make them fit to survive in their current conditions.

-Struggle for survival: As stated the lack of nutrient availability initiates a certain struggle/ fight for access to food, shelter between the organisms of a species and only the fittest will survive.

Question 2

What is variation and what are some of its sources?

Answer 2

Variation is the difference or changes in one organism compared to others in its species.
3 main sources:
- mutation, this is not one of the most seen sources however it possible. Mutation is when a piece of a sequence of DNA is changed. changes in the DNA cannot affect phenotypes however it can change genectic information which could possibly cause genetic diseases.

• meiosis in meiosis there is a process where chromosomes pair up and exchange different versions of the same gene from parent cells. this creates 4 genetically different cells which creates a varying organsims from the ones before.

-Sexual reproduction during sexual reproduction millions of sperm cells are released in ejaculation however only one can fuse with the ovum. this randomness accounts for variation.

Question 3

What’s the relationship between overproduction and competition in an ecosystem?

Answer 3

When there is an overproduction of offspring, it creates a supply and demand that is not sustainable by the environment, meaning the demand outweighs the supply. This creates a competition between organisms. They now have to compete for resources in order to survive and only the best fit organisms will survive.

Question 4

selection pressure

Answer 4

This is a factor that can affect the success of parts of a population and influence change in allele frequencies.
for example effects of the following on an ecosystem
Abiotic factors - temperature changes, humidity, and light availability.
Density-independent factors: water pH, concentration of gases in the air (CO₂, nitrogen, methane), and availability of certain minerals.

Question 5

What is intraspecific competition?

Answer 5

Intraspecific competition is when organisms in the same species of an organism compete for survival. either over food, shelter, or even mates. Typically the organisms with better fitness (characteristics compatible with the environment) survive compared to lesser fitness organisms (characteristics that are less compatible with environment). This is a process driven by natural selection.

Question 6

What is the difference between heritable and acquired traits

Answer 6

Heritable traits are traits that are determined by DNA and not only affects you but also your offspring and their offspring; it can be passed down, hence heritable. However, acquired traits are simply traits that an organism has picked up during its time alive, they are typically caused by the environment or experiences had. For example, a human learning to swim.

Question 7

What is sexual selection?

Answer 7

Sexual selection is when certain organisms possess useful traits that help attract mates, therefore positively influencing their reproductivity compared to other organisms.

Question 8

Modelling selection pressures

Answer 8

This is a controlled experiment where selection pressure are modelled and applied to a subject to see the effect of each.

Question 9

Explain what is considered a stable ecosystem.

Answer 9

A stable ecosystem is an ecosystem that has a maintained balance, whether it be between animals and plants that are present for biodiversity, nutrients to feed those animals and plants, or natural resources that provide the food and shelter for the animals and plants.

Question 10

What is a sustainable ecosystem, and what is a good example of this?

Answer 10

This is an ecosystem that can support itself without help from the outside; it is able to provide the needs of its population/inhabitants.
a good example of a sustainable ecosystem is the amazon rainforest
The main source of water in the forest is said to be the river; it is thought that this is why the trees in the forest grow so dense and cling together. The change in availability of water causes the trees to adapt and evolve to grow wider, denser and closer to each other to form a resource sharing network.

Question 11

What are some requirements for sustainability?

Answer 11

GNEC
Genetic diversity—with genetic diversity, if there was a case where an extinction event were to happen the chances of an entire population being wiped is less likely as there may be an organism that possesses the traits to survive the event. but if we were all genetically the same, the entire population could be wiped out.

Nutritional recycling- all resources have their limit this is why there are natural cycles put in place to prevent wastage for example the nitrogen, carbon and water cycle.
Supply of energy - sunlight is harvested by plants and algae for photosynthesis. they are eaten and passed down the food chains and webbs allowing for the transfer of energy in the form of organic molecules.

Climate change— as long as climate change remains within tolerance levels, an ecosystem can remain sustainable

Question 12

What are some types of tipping points

Answer 12

There is a tipping point where an ecosystem reaches a point where it can no longer go back to being able to support itself, no longer being able to be sustainable. There is also another tipping point where it goes from sink to source; for example when climate change cause tree browning and dry soil which initiates forest fires that release carbon dioxide, trees used to be a sink that collects carbon dioxide but now its a source for it.

Question 13

Mesocosm

Answer 13

a small enclosed ecosystem in controlled experimental conditions that is used to determine the specific effects if each abiotic and density-independent factor.

Question 14

What is a keystone species? Give an example.

Answer 14

A keystone species is a species that plays an important role in maintaining biodiversity in its ecosystem. For example, the sea star keeps mussels in check and prevents their overproduction, which allows for other organisms to feed, find shelter, and reproduce successfully.

Question 15

Explain the Trophic cascade

Answer 15

A trophic cascade is when there is a removal or addition of an apex predator and changes happen going down the food chain/web.

Question 16

How to be sustainable when harvesting natural resources

Answer 16

just ensure the harvesting doesnt out do the ability

Question 17

what is eutrophication?

Answer 17

This is when an overgrowth of plants in large bodies of water is due to the leaching of nutrients into large bodies of water.

Question 18

What is sustainable agriculture, and what are some issues that prevent it?

Answer 18

Sustainable agriculture is agriculture done correctly, able to regenerate, biodiverse, and with reduced carbon dioxide output.
issues = Sclf

• Soil erosion occurs when large crops are cut down, leaving the ground exposed. The topsoil is then blown away or washed away by rain. This layer typically contains most of the nutrients needed, leaving the remainder nutritionless.
• Carbon dioxide Footprint, the carbon footprint for agriculture is approximately. 12%.

1) Carbon is released from the petroleum-run farming machinery

2) the removal of naturally diverse trees and vegetation to make room for farming desires vegetation. This increases carbon dioxide in the air.

3) Fertilizers are produced using petroleum-run machines

4) Leaching- in order for nutrients to be useful to plants, they need to be water-based. When rain falls, it dissolves the nutrients and washes them away from the roots and into a body of water, leaving the roots with nutrientless soil.

5) Frequent chemical fertilizer usage results to eutrophication, which causes decomposition, releasing more CO2 into the air.

Question 19

What is micro and macro plastics and why are they a problem?

Answer 19

Microplastics are plastics that are sized less than 5 mm they were once macro but were broken down by machinery.
Macroplastics these are plastics that are larger than 5 mm

plastic is not biodegradable, and its even worse if their tiny because they can be consumed by marine life which will remain in them. The animals are caught and eaten causing humans to ingest them.
Another reason is that they are literally killing marine life

1) turtles eat plastic sacks thinking its a jellyfish

2) medium sized creatures get caught in soda packaging rings

3) pieces of plastics are caught and fed to the young marine chicks

Question 20

What is rewilding, what are some types of rewilding? Give an example

Answer 20

rewilding is a method scientist use to protect and conserve natural processes.

• introduction or removal of a apex predator
• reduce human activity
• reduce harvesting natural resources in the area

Hinwai reserve in new Zealand. Privately owned by a trust, however open to the public and was created to foster native vegetation and wildlife.

Question 21

What is the greenhouse affect?

Answer 21

The greenhouse affect is the way an atmosphere retains heat and keeps warm.

Question 22

what are greenhouse gases

Answer 22

Carbon dioxide and methane are gases that trap infrared radiation.

Question 23

What is infrared radiation?

Answer 23

When the sun hits on an object, the object absorbs the energy, and it heats up. This is called radiation. Infrared radiation is when the object re-radiates that energy to another.

Question 24

What is climate change and what role do Greenhouse gases play in its progression?

Draw a representation as well

Answer 24

Climate change - this is changes in the temperatures and weather of the atmosphere over various years.

Greenhouse gases can be found in the atmosphere surrounding the Earth. Greenhouse gases are the way heat is retained by the earth because they absorb infrared radiation and transform it from shortwave radiation to longwave radiation and reradiate it in all directions, including back to the surface. This is known as the greenhouse effect. GHGs take part in climate change because more in the atmosphere means more heat is being retained, causing an overall increase in temperature over the years.

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Question 25

What is anthropogenic?

Answer 25

This is anything caused by human activity; for example, the burning of fossil fuels causes climate change.

Question 26

What is albedo?

Answer 26

Albedo is a surface's ability to reflect light. lighter coloured objects have high albedo, which means they absorb light less and reflect it more. Darker coloured objects have lower albedo, which means they absorb more light and reflect less light.

Question 27

how is new cells generated and why is it important to generate new cells?

Answer 27

1) How - new cells are generated by cell division: Cell division is when two or more daughter cells are created by copying one mother cell. depending on if your a multi- or singular chromosome organism you divide by binary fission or meiosis and mitosis binary fission is cell division for single chromosome organisms a) cells copy DNA b) Daughter cells become attached to to different sides of the plasma membrane, and the membrane splits to make two from one. however the other its through mitosis and meiosis mitosis is the creation of two identical daughter cells and meiosis is the creation of 4 genetically different daughter cells. new cell generation is important because if its not done single cell animals wouldnt survive and multi wouldnt be able to reproduce, grow and repair damages to the body.

Question 28

How does cytokinesis happen to the different cell types?

Answer 28

Animal cells - in these cells small pinches are made in the cytoplasm until cleavage furrows appear along the membrane plant cells - vesicles build up in between the poles of the cell, harden and form what is called a cell plate.

Question 29

Is cytoplasm division always equal? True or false, give an example and explain what you mean.

Answer 29

False - cytoplasm division can be equal/ fair, at least one copy of each organelle from the mother cell into the daughter cell. We said at least one because a daughter cell can have one or more mitochondria, but it needs at least one to power the cell. But it can also be uneven. for e.g oogenisis This is where 3/4 of the genetically different daughter cells donate organelles to create a 4th cell. This cell doesn't make it past the implantation stage because it is not fully equipped with the things needed to survive.

Question 30

Can nuclear division happen after cell division? Why, yes? Why not?

Answer 30

NO - the nucleus needs to be copied before it divides, or only one cell will have a nucleus and the other one will be anucleate; it will not have the instructions to carry out its functions.

Question 31

What is DNA condensation?

Answer 31

DNA condensation is when coiled DNA is wrapped around proteins called histones to help prevent them from tangling and breaking. This results in a supercoiling that gives it the double helix shape that everyone is familiar with.

Question 32

How is the movement of chromosomes possible? Draw an image explaining

Answer 32

The movement of chromosomes is possible thanks to several important structures. 1) Centrosome—this is an organelle that organize the microtubule spindle fibers 2) Microtubule spindle fibres - these structures have a directionality because one end is negative and one end is positive that is used by proteins to guide chromosome movements. 3) motor proteins- this is what actually moves the chromosomes. Motor proteins can either use microtubles as tracks or they can attach to two microtubules and using ATP for energy cause one two slide over the other creating a motion that moves the chromatids to either side. More specifically, they are many different microtubules found in the cell, some overlapping, some not. When a cell is ready to separate its chromosomes, the motor protein between overlapping microtubules activates and causes one microtubule to slide over the other. This action causes the poles in the centromere to be pushed away from each other, and given that one chromatid is attached to each pole, they are pulled away from each other.

Question 33

sing the meiosis and mitosis song!!!!!! what are the steps of meiosis and mitosis?

Question 34

How is Down syndrome caused? What is disjunction?

Answer 34

A human is supposed to have 46 chromosomes; however, there are some cases where there is an addition or subtraction to the amount of chromosomes a human has. This is called disjunction. A good example of disjunction is Down syndrome. This is where a person has an additional chromosome, making it 47 instead of 46. Typically when the mother is undergoing meiosis during the stage anaphase 1, the 21st chromosome doesnt split but instead moves to the poles whole and the egg is made with 2 21st chromosomes. Then When the egg is fertilized, sperm contributes another 21st chromosome, causing 3 21st chromosomes to be present.

Question 34

How exactly is genetic diversity achieved?

Answer 34

In meiosis there is a stage called prophase 1 where the process called crossing over takes place. During crossing over, the homologous chromosomes each break at the exact same spot on their chromatid, the chromatid and its non sister chromatid twist around each other, and replace each piece's initial spot forming recombinant chromatids.

Question 35

how does random orientation contribute to variety?

Answer 35

In metaphase the chromosomes are lined at the equator randomly after which they are pulled to opposite poles of the cells. Which chromosomes wind up at which pole is up to chance which is random orientation and this contributes to variety because its a guarenteed different chromosome at either pole majority of the time.

Question 36

Explain what solvation is and how exactly it happens.

Answer 36

Solvation is the interaction of a solvent with particles of a solute. for e.g solvation with water as the solvent water has certain properties that allows it to dissolve polar molecules water is a polar molecule itself. water forms hydrogen bonds that are strong but ultimately weaker than covalent bonds depending on whether or not a molecule is polar or nonpolar, water will be able to dissolve it. if a molecule is polar, when placed in an environment where it is surrounded by water, due to electrostatic attraction, the water molecules will surround the solute, breaking a few hydrogen bonds between water molecules in the process. Where the bonds are broken, the positive end of the molecule will be attracted to the negatively charged atom (Oxygen) in a water molecule, and the negative end of the molecule will be attracted to the positively charged atom in the water molecule (hydrogen). depending on if the solute is ionic or a molecule, the bonds within it will break and form new bonds with the water molecules, breaking apart the solute, i.e., dissolving it (ionic), or it will simply attract and repulse the atoms, pulling apart the molecule and dissolving it without creating and breaking covalent bonds (molecule).

Question 37

State and explain the different solute concentrations.

Answer 37

Hypotonic solution - This is when an outer environment has a lower solute concentration and higher water content than the inner environment. Hypertonic solution- This is when the outer environment has a higher solute concentration and lower water content compared to outer environment isotonic solution—this is when the outer and the inner environment have an equal solute concentration and water content.

Question 38

What are aquaporins, and why are they important?

Answer 38

The cell membrane has a polar and nonpolar side. Aquaporins are proteins that form water channels in the cell membrane that allow for water, which is polar and can't pass through the nonpolar outer layer easily, to move in and out of the cell. This is important for facilitating osmosis, which helps transport water to the needed areas of the body. If not for aquaporins, water regulation in the cell would be much slower, which could lead to shrinking of the cell from lack of water or bursting from too much water.

Question 39

What is dynamic equilibrium?

Answer 39

This is when both inner and outer conditions are equal, making them isotonic. when this happens there is little movement of water molecules but there is no net movement of water. This is dynamic equilibrium

Question 40

Describe the process of DNA replication.

Answer 40

In DNA replication, an enzyme called helicase breaks the hydrogen bonds between the nitrogenous bases in the DNA, causing it to split down the middle and become two single strands. A protein called single-strand binding protein binds to the unzipped DNA and prevents it from reforming the hydrogen bonds. While ahead of the replication fork, an enzyme called gyrase relieves the torsional pressure caused by the unzipping of the DNA molecules. As all of these are happening, another enzyme called primase sets primers so that the enzyme DNA polymerase III knows where to start coding for the strands. Depending on whether a leading or lagging strand needs to be synthesised. The coding will be discontinuous or continuous. If a leading strand needs to be synthesised (template strand is from 3' to 5'), it will need to be synthesised in the same direction that polymerase adds bases, and therefore, DNA polymerase III can synthesise a continuous strand needing only one primer to start. However, if it is a lagging strand (template strand is from 5' to 3'), then the bases need to be added in the opposite direction to how DNA polymerase adds bases, and it will therefore need a primer before each fragment coded for, making the strand discontinuous. The fragments mentioned are called the Okazaki fragments. When the DNA is completely replicated, DNA polymerase I removes the primers, and the enzyme ligase connects the fragments to each other. In case a mistake has occurred when placing the bases, the polymerase enzymes have exonuclease activity, which allows them to stop, remove, and replace with the correct base.

Question 41

How is DNA created in terms of conservancy

Answer 41

DNA is semi-conservative meaning the DNA made from the first replication are 50% original and 50% new.

Question 41

what is DNA and the role of DNA replication?

Answer 41

Dna is the molecule that holds the code for the creation of uniqueness in all living things. the role of DNA replication is to ensure that there is enough DNA so that all cells can have it after cell division. it is important for cells to have it so that growth and repairing of the body can take place successfully.