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?
Recall that a cell is defined as the basic, structural and functional unit of life.
Generally, cells are put into two types based on the presence or absence of a well-defined nucleus within it, alongside their specific setups. These are:
Prokaryotic cells (or prokaryotes) are unicellular organisms lacking a definitive nucleus. They have a cell size ranging from 0.1 to 0.5 µm (micrometer) in diameter, and are typically in the domain of archaea, cyanobacteria and bacteria. Generally, prokaryotes are found everywhere on earth, be it on land, water and air, including inside living organisms.
The prokaryotes 'archaea' are ancient organisms that thrive under extreme conditions. As an instance, Pyrolobus fumarii is an archaea that lives in hydrothermal vents with temperatures around 113 oC or 235 oF.
The Picrophilus are another group of archaeans that live in soils with an acidic pH as low as zero. In fact, they are the most acid-tolerant organisms known on earth.
The methanogens are another group of archaeans found in places without oxygen (anaerobic environment) such as hot springs, intestines of animals and marshes. Such methanogens include Methanobrevibacter gottschalkii, Methanococcus maripaludis, Methanogenium frigidum, Methanopyrus kandleri, Methanosaeta concilii, Methanosarcina barkeri, and Methanosphaera stadtmanae.
Cyanobacteria are prokaryotes, and were formerly termed as blue-green algae. They are known to manufacture their own food through a process termed photosynthesis. They are able to do this as a result of the green pigment (chlorophyll) present within their cell. They constitute a large number of the aquatic ecosystem, that is: oceans, seas, rivers, lakes and ponds respectively.
Bacteria are considered as one of the most popular prokaryotes on earth due to their harmful and beneficial actions to other organisms. For instance, numerous beneficial bacteria are present in the colon of humans and ruminants. However, some could be harmful; for example, certain strains of Escherichia coli (E. coli O157:H7) present in the intestines of animals.
Note: the population of bacteria inside the human body is higher than the total number of human beings living on earth.
The above image will serve as a reference towards the explanation on various structures of a prokaryotic cell.
The prokaryotic cell is bounded by a plasma membrane (or cell membrane), cell wall and an outermost capsule. The cell membrane is semipermeable. This means that it can allow the entry and exit of certain substances, while denying others. Also, it can be utilized for respiratory activities.
The cell wall is present just after the cell membrane and before the capsule. It is made up of peptidoglycan (or murein), which is a polymer of sugars and amino acids. It functions to protect the cell from unfavorable external conditions, prevents it from bursting, and also gives the prokaryotic organism its shape.
Alongside the cell wall, an outer protective layer called capsule may also be found in the cells of bacteria. They are formed from capsular polysaccharides (CPSs) with varying structures. The capsule functions to preserve and protect the cell form being digested or dissolved (through phagocytosis) by enzymes or other foreign cells. Together with the slime layer, it aids the attachment of the bacteria to nutrients and adjacent cells. Meanwhile, understand that the capsule have also got good water retention ability.
Prokaryotic cell do not have a definite nucleus, neither do they have nuclear membrane. They have a chromosomal Deoxyribonucleic Acid (DNA), typically present on a single chromosome. Such DNA is crucial for their sexual reproduction. However, they may also have non-chromosomal DNA materials called plasmids, and these are not required in reproduction. The location of the prokaryotic genetic materials are somewhere in a cytoplasmic region termed as nucleoid, and this could be spiral, spherical, rod-like or irregular in shape.
The nucleoid in prokaryotes is the region in the cytoplasm where genetic material is located.
Note: Plasmids are non-chromosomal DNA structures in prokaryotes. As a result, they are not involved in reproduction.
Prokaryotic cells often have pili. These are short proteinous hairlike structures used for attachment to the surface of other cells. They may be utilized for the cell's movement, but more importantly, they initiate the infectious and virulent properties of harmful bacteria. However, some prokaryotes may also have a whiplike structure called flagella which serves locomotary purposes for the cell.
The appendages for locomotion are called protrusions, and are often found on the surfaces of prokaryotic cells. They include flagella, fimbriae and pili.
The cytoplasm is a gel-like fluid filled space within the plasma membrane of a prokaryotic cell. It is composed mainly of cytosol, ribosomes, inclusions, cytoskeleton, enzymes and salts.
The mitochondria, golgi apparatus and endoplasmic reticulum are all absent in prokaryotes. However, ribosomes may be present, and are involved in protein synthesis.
Reproduction in prokaryotes can occur either sexually or asexually. Asexual reproduction is typically through a process termed binary fission, while sexual reproduction occurs through gene recombination.
Gene recombination in prokaryotes can be achieved via the following methods:
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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: