Topics in BiologyDifference between plant cell and animal cell Nucleus explained with its structures Nucleus explained with its types and functions Organelles of the cell explained with their characteristics Eukaryotic cell explained with its characteristics Prokaryotic cell explained with its structure Characteristics of prokaryotic cell Concept of cell Cell theory in biology Importance and limitations of ecological pyramid Protists explained with their characteristics Contents of the scrotum: Epididymis, vas deferens, spermatic cord and cremaster muscle Tropical savanna explained with its characteristics Concept of ecological pyramid Hindbrain: Medulla Oblongata and its features Food web explained with examples Biology Scheme of Work, SS1, First Term Biology Scheme of Work, SS1, 2nd Term Biology Scheme of Work, SS1, 3rd Term Male accessory sex organs: Seminal vesicles and bulbourethral glands
Academic Questions in Biology
From the above diagram, which of the organ below isn't a requirement for the male reproductive system?
C. Glans Penis
E. Bulbourethral Gland
A walnut shaped male accessory sex organ located between the bladder and penis is the _____.
A. Ductus Ejaculatorii
B. Bulbourethral Gland
C. Prostate Gland
D. Ductus Deferens
E. Seminal Vesicles
In a food chain, the primary consumers are classified under trophic level _____.
Cold blooded animals are referred to as _____.
F. None of the above
All reptiles are vertebrates.
_____ cells are responsible for the formation of osteoblasts.
_____ is a bone that constitute the axial skeleton.
Which of the following is false concerning cartilages and bones?
All living organisms are composed of one or more cells. In light of this, a cell refers to the smallest, basic, structural and functional unit of life.
Depending on the type of cell constituting an organism, a nucleus may be distinct (clearly defined) or not. In this regard, cells are generally classified into two types. These are:
Please read on prokaryotic cell here.
Recall that an eukaryotic cell has a clearly defined nucleus. Therefore, our discussion on the types of cell based on their nuclear distribution (or number of nucleus) will dwell on eukaryotes. To this end, eukaryotic cells may have a single, double, or more nuclei present within it at a specific point in time. Interestingly, certain eukaryotic cells may even lack nucleus at a point in their lifespan.
Certain cells without nucleus at a point in time are still considered as eukaryotic since they were once nucleated at one point in their lifespan.
Cells can be categorized based on the distribution (or number) of nucleus present within them. They include:
Image showing the various distribution of nucleus in an eukaryotic cell.
Enucleate cell refers to a cell without nucleus at a point in its lifespan. As a result, they do not have genetic materials, and will therefore lack the capacity of cell division.
Examples of eukaryotic enucleated cells (nucleus lacking eukaryotic cells) include matured red blood cells, osteoclasts and mature sieve tubes cell of phloem in plants.
Note: Enucleation is a concept in microbiology that refers to the removal a cell's nucleus, and replacing it with a different nucleus. This may be applied in the production of hybrid animals and plants. However, scientist had utilized this knowledge of enucleation in achieving organism cloning.
Uninucleate cell has only one nucleus. These are generally referred to as monokaryotic cells, and are present in most plants and animals. Examples of uninucleated cells include smooth muscle cells, cardiac muscle cells, leukocytes, neurons, keratinocytes and adipocytes in humans.
Binucleate cell have two nuclei at a time, and are referred to as diakaryotic. Some cells of the liver, bladder, cartilage and cardiac muscle are examples of binucleated cells. Also, a protist like paramecium is unicellular and binucleated.
Meanwhile, understand that most cancerous cells are binucleated.
Multinucleate cell contains more than one nuclei at a point in time. They are generally termed as polynucleated, polynuclear or syncytium. Examples include cells of the skeletal muscle fiber, blood cells, bone marrow cells, latex cells in plants, tapetal cells of plants, storage cells of douglas-fir seeds, latex vessels and slime mould cell.
Recall that the nucleus is regarded as the most important organelle in a cell. This is true because it coordinates the activities of the cell. Below are the functions of the cell nucleus:
The nucleus is the center of control in the cell. It coordinate and regulates various cellular activities. Examples of such cellular activities include growth, reproduction and metabolism.
Please read on homeostasis here.
The nucleus can initiate a programmed cell death called apoptosis. This action of the nucleus can play a role in cancer prevention.
The nucleus houses DeoxyRibonucleic Acid (DNA). The DNA is the genetic material of the cell, and they make up the chromosomes.
You can read interesting facts for students in biology here.
DNA replication and its eventual transcription into RNA occurs in the nucleus.
The nucleus serve as the information center of the cell. This is true because it houses the organism’s genetic code, which determines the amino acid sequence, and these are crucial for the cell's proper functioning.
Please read the concept of organelles here.
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Amazing facts in Biology
Russia is home to the largest area of forest in our world with a land mass of 815 million hectares
Giant squid lives deep in the ocean and they have the largest eyes in the world
The movements of the fingers are controlled by muscles of the palms and forehands
Platypus (sometimes referred to as the duck-billed platypus) is an egg-laying, semiaquatic mammal found in eastern Australia. It has no stomach and as such, its food goes from the mouth through the esophagus and directly to their intestines.
Pufferfish contain a toxin called tetrodotoxin. This makes them foul tasting and poisonous to predators. Tetrodotoxin is about 1,200 times more poisonous than cyanide, and there is enough toxin in one pufferfish to kill 30 adult humans. Unfortunately, there isn't any known antidote to this poison.
Interestingly, a delicacy in Japan (called fugu) is made from pufferfish. This meal is very expensive, and must be prepared by trained and licensed chefs. An improper preparation of fugu may lead to the customer's death. Sadly, such deaths are recorded annually
Wombats are the only animal with a cube-shaped poo. They can stack up these cube-shaped poo, marking their territory with it
Robert Wadlow (1918–1940) remains the tallest man ever recorded in the Guinness World Records. He was an American who stood at 8 feet, 11 inches.
An abnormally enlarged pituitary gland had resulted into Robert Wadlow's giant size.
Cockroach is the fastest land animal on six legs
Like humans, all apes laugh when tickled
An ostrich's eye is bigger than its brain
Notable points in Biology
An artery is composed of three layers:
The outermost layer is termed tunica adventitia (or tunica external). It consist mainly of collagen fibres and connective tissues that anchors the arteries to other nearby tissues.
The middle layer is named tunica media. It is made up of smooth muscles and elastic fibres that supports the artery in conveying blood at high pressures.
The inner layer is called tunica intima (or tunica internal). It is lined by a smooth tissue called endothelium, and is made up of a fine network of connective tissues.
All living organisms possess various features in order to survive in their environment. This is the concept of adaptation. As an instance, a fish is able to live in water because it has gills and fins.
Also, a camel is able to survive in the desert because it has large feet to aid walking on sand without sinking. It also has long eyelashes to help protect it from the blowing sand and wind.
Plants are also able to live in different habitats because they have the required adaptive features towards that habitat. For instance:
Plants that live in/on water are termed hydrophytes.
Plants that live on land with moderate amount of water are termed mesophytes.
Plants that live on deserts or arid lands are termed xerophytes.
The point is:
All organisms have various features on them that enables them adapt in their habitat
For a thing to be considered living, it must possess all the basic characteristics of life. These include:
Irritability or Sensitivity
During strenuous exercises like sprinting or running, your body may actually work in the shortage of oxygen. During this time, your body owes oxygen (called oxygen debt) and it must be replenished or repayed after the exercise is stopped. This is why you breathe excess of oxygen after you stopped the exercise.
This is the concept of anaerobic respiration
A food chain is a diagram that shows the relationship between plants and animals within a habitat on the basis of how they rely on each other for food.
Note: Habitat is a place where an organism live. It is of three types: