<span>Levels of OrganizationIn unicellular (single-celled) organisms,
the single cell performs all life functions. It functions independently.
However, multicellular (many celled) organisms have various levels of
organization within them. Individual cells may perform specific
functions and also work together for the good of the entire organism.
The cells become dependent on one another.Multicellular organisms have
the following 5 levels of organization ranging from simplest to most
complex:<span><span>LEVEL 1 - Cells<span><span>Are the basic unit of structure and function in living things.
</span>May serve a specific function within the organismExamples- blood cells, nerve cells, bone cells, etc.</span></span><span>LEVEL 2 - Tissues<span>Made up of cells that are similar in structure and function and which work together to perform a specific activity
Examples - blood, nervous, bone, etc. Humans have 4 basic tissues: connective, epithelial, muscle, and nerve.</span></span><span>LEVEL 3 - OrgansMade up of tissues that work together to perform a specific activityExamples - heart, brain, skin, etc.</span><span>LEVEL4 - Organ Systems
<span>Groups of two or more tissues that work together to perform a specific function for the organism.
Examples - circulatory system, nervous system, skeletal system, etc.
The
Human body has 11 organ systems - circulatory, digestive, endocrine,
excretory (urinary), immune(lymphatic), integumentary, muscular,
nervous, reproductive, respiratory, and skeletal.</span></span><span>
LEVEL 5 - Organisms
<span>
Entire
living things that can carry out all basic life processes. Meaning they
can take in materials, release energy from food, release wastes, grow,
respond to the environment, and reproduce.
<span>Usually made up of organ systems, but an organism may be made up of only one cell such as bacteria or protist.
</span>Examples - bacteria, amoeba, mushroom, sunflower, human</span></span></span></span>
Answer:
QUESTION 1:
a. They undergo unequal cytoplasmic division during meiosis- eggs
b. Their chromosomes have undergone genetic recombination and independent assortment- both gamete types
c. They contain specialized secretory vesicles called cortical granules just under the plasma membrane- eggs
d. They are characterized by a flagellum. Most of these gametes die without ever completing meiosis- sperm
e. The acrosomal reaction occurs in these cells- sperm
f. They can be derived from any adult cell type- neither gametes
QUESTION 2:
c) The egg is surrounded by a mineralized shell added before the egg exits the body.
Explanation:
a) Female reproductive cells undergo meiosis to produce one large egg and three polar bodies. However, an unequal cytoplasmic division occurs in favour of the large egg.
b) Since both egg cell and sperm cell are produced via meiosis and meiotic division involves the processes of genetic recombination and independent assortment, hence, both gamete types have their chromosomes underg genetic recombination and independent assortment.
c) Egg cells contain specialized secretory vesicles called cortical granules just under the plasma membrane. This cortical granules help prevent more sperms from fertilizing the same egg after it has been fertilized.
d) Sperm cells possess flagellum for motility in the female reproductive tract. Most of the sperm cells die without ever completing meiosis.
e) Sperm cells possess an head-covering structure called ACROSOME. Acrosome reaction is the process undergone by sperm cells permeate the zona pellucida of the egg.
f) Gametes are specifically derived from adult reproductive cells and hence, NEITHER TYPE OF GAMETE can be derived from any adult cell type
QUESTION 2:
The egg in Sea urchins is surrounded by a mineralized shell added before the egg exits the body to the external environment. This does not occur in the humans because the egg does not leave the body but fertilized internally.
Answer:
See explanation below
Explanation:
<em>Non-disjunction occur as a result of lack of separation of homologous chromosomes during meiosis. </em>
As a result, the gametes (the daughter cells formed) produced end up having extra or lesser chromosomes as compared to a normal gamete.
When a gamete with extra chromosome fertilizes a normal gamete, the resulting offspring will have an extra chromosome (trisomy condition).
On the other hand, when a gamete with one less chromosome than normal fertilizes a normal gamete, the resulting offspring will have one less chromosome than normal offspring (monosomy condition).
Assuming a chromosome with Aa gene undergoes non disjunction during meiosis, the resulting gametes either contain both A and a chromosome or contain no chromosome at all.
If Aa gamete is fertilized by a normal haploid sperm (a), the resulting zygote will have the genotype Aaa.
If a gamete with no chromosome at all fertilizes a normal haploid sperm, the resulting offspring will have the genotype a.
Answer:
Longest interval during which no tree-cutting sample occurred: 9 years (1203 AD - 1212 AD)
First year in that interval: 1203 AD
Explanation:
Lets complete the question first.
Q) A study uses tree rings to determine the year in which a tree was cut. The data is shown in the leaf and stem diagram in the ATTACHMENT.
The three digits number in the left column represents centuries and decades AD. The numbers on the right represents the years.
For example, consider the first input in the diagram
119 | 5 6
which means it represents 2 samples.
1195 AD, 1196 AD.
The longest interval with no tree-cutting samples is found from 1203 AD to 1212 AD.
Answer: The estimated population is 1250 mice
Explanation: The method use was marked and recapture, in which individuals are marked in the first capture and after some time biologist trap a new group of individuals that can be or not marked
Whit this data is possible to estimate the size of a population applying the Peterson method but is important to make some considerations such as:
1. All indivuals have the same probability to be capture
2, The population remain constant in terms of birth and death rate.
Taking this into account, the formula that allows to determine the size of the population is:
N=CM / R
where N is the size of the population, C is number of indivuals trapped in recapture, M is number of individuals marked in the first capture and R is the number of marked animals trapped in recapture
In this case:
N = 250 * 200 / 40 = 1250