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Worksheet on Nitrogen cycle PDF

Nitrogen cycle is the cyclic movement of nitrogen (N2) between atmosphere, organisms and soil. Nitrogen is an essential element required for the synthesis of bio-molecules like proteins, DNA, vitamins, chlorophyll, alkaloids etc.
 Learn more: Nitrogen Cycle
 Learn more: Nitrogen Cycle (Video) 
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SAT Biology E/M Practice Test on Classical Genetics- Quiz on Mendelian Genetics

Questions from Meiosis, Mendelian Genetics-ABO blood group, Pleiotropism

1. Colorblindness in humans is
in equal proportion in both sexes
caused in females by a heterozygous genotype
inherited by males from their male parent
caused in males by a homozygous genotype
caused by a recessive allele
2. A ratio of 3:1 in the phenotype of an organism occurs when
crossing over has occurred in Anaphase II
the alleles are incompletely dominant
only recessive traits are involved
alleles segregate during meiosis
only dominant traits are involved
3.Which of the following is not indicated by Mendel’s experiments?
independent assortment
incomplete dominance
4. In a heterozygous monohybrid cross, the dominant trait can be expressed in the phenotype of the F1 --- of the time.
0 percent
25 percent
50 percent
75 percent
100 percent
5. Homologous chromosomes line up in pairs in
metaphase I
metaphase of mitosis
metaphase II
prophase of mitosis
6. Trisomy 21 in humans is the result of
polygenic inheritance
7. Which of the following blood types are possible if the parents are A and O blood types?
A, B, and O
A and O
O only
B and O
AB only
8. Which of the following would indicate a test cross, where T represents the dominant, tall, trait and t represents the recessive, short, trait?
Tall × Tt
Tall × TT
TT × Tt
Tall × tt
short × tt
9. Which of the following would be the result of a true dihybrid cross?
10. ---refers to one gene affecting many traits
Score =
Correct answers:

Practice more Quiz from GeneticsGenetics TerminologyMeiosis
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SAT Biology E/M Practice Test on Cell And Molecular Biology - Quiz on Cell and Cell Cycle

Questions from Cellular and Molecular Biology - Cell Structure - Cell cycle
SAT Biology E/M Practice Test on Cell And Molecular Biology
1. Which of the following is NOT involved in the synthesis of proteins?
smooth ER
Golgi body
rough ER

2. Which of the following produces ATP during aerobic respiration?

3. The -----is a rigid structure that gives the cell support in plants.
cell wall

4. If the concentration of a solute differs across a membrane permeable only to water, water will move across the membrane by
facilitated transport.
active transport

5. Which of the following often distinguishes plant cells from animal cells?
plasma membrane
rough ER

6. Which of the following stages of the cell cycle occurs immediately prior to mitosis?

7. Chromosomes replicate in

8. Cytokinesis begins in

9. Chromosomes are pulled to opposite poles of the cell

10. Identify the correct eukaryotic cell cycle
G1 to G2 to M to S to mitosis
G1 to S to G2 to M to cytokinesis
G2 to M to S to G1 to cytokinesis
G1 to G2 to S to M to karyokinesis
S to G1 to G2 to M to cytokinesis

Score =
Correct answers:

For More Practice Tests: Cellular and Molecular Biology - Cell Structure- Cell cycle
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SAT Subject Test Biology E/ M Practice Test - Cellular and Molecular Biology Quiz on Biological Chemistry

Questions from
Biological chemistry - Water and its properties- Functional groups - Carbohydrates- Lipids (fats and oils) - Proteins Structure - Enzymes -Nucleic acids
1. In the reaction rate versus substrate concentration graph below, the curve plateaus because
the cofactor is locked in an inactive conformation.
the active site is saturated with substrate.
a noncompetitive inhibitor is present
a competitive inhibitor is present.
all the substrate has been converted to product.
2. The element found in all amino acids that is NOT found in carbohydrates is
carbon (C)
sulfur (S)
3. Which of the following terms does NOT refer to an example of a weak force of interaction between two molecules?
electrostatic bond
Van der Waals bond
hydrophobic bond
hydrogen bond
covalent bond
4. Which if the following is NOT found in DNA?
deoxyribose sugar
5. Which of the following are weak forces usually associated with biological molecules?
covalent bonds
ionic bonds
hydrogen bonds
electrostatic interactions
both hydrogen bond and electrostatic interactions
6. Which of the following would NOT have hydrophilic properties?
ionized molecules
long hydrocarbon chains
polar molecules
molecules in aqueous solution
7. Which of the following is NOT a property of water?
very good solvent
hydrophilic properties
strong surface tension
density as a solid is less than that as a liquid
hydrophobic properties
8. Elements used for making molecules found in living systems must
be hydrophilic
be covalent
contain nitrogen and sulfur
be water soluble and ionic
be suitable and available
9. A polypeptide that is ten amino acid units long is split into several small fragments, and the sequences of some of the fragments are discovered. The fragments are lys-trp-arg, lys-asp-ala-gly, pro-gln-his-lys, and arg-pro-gln. What was the primary source of the polypeptide?
10. Which arrow(s) point to a peptide bond?
1 and 4
2 and 5
Score =
Correct answers:

For More Practice Tests: Carbohydrates- Lipids (fats and oils) - Proteins Structure - Enzymes -Nucleic acids
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IGCSE Biology Notes on Five Kingdom Characteristics

Five kingdom Classification proposed by R. H. Whittaker in 1969. The five kingdom are 

Kingdom Prokaryotes (Kingdom Monera): The Kingdom Of Prokaryotes
Monera  includes bacteria, cyanobacteria, mycoplasma and actinomycetes.

Kingdom Protists (Kingdom Protozoa) :The Kingdom Of Unicellular Eukaryotes)
Protists includes diatoms, euglenoids, dinoflagellates, slime moulds and protozoans.

Kingdom Fungi: The Kingdom Of Multicellular Decomposers
Fungi   includes multicellular or multinucleated achlorophyllous spore producing eukaryotic organisms like Pencilium, Rhizopus, mildews, mushrooms, rusts, morels, puff balls, bracket fungi etc.

Kingdom Plants (Kingdom Plantae) : The Kingdom Of Multicellular Producers
Plantae includes photosynthetic multicellular organisms i.e., algae, bryophytes, pteridophytes, gymnosperms and angiosperms.

Kingdom Animals (Kindom Animalia) :The Kingdom Of Multicellular Consumers
The main group represented in the animal kingdom are sponges, coelenterates, annelids, arthropods, molluscs, mammals, reptiles, fishes, amphibians and birds. 
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IGCSE Biology Notes - General Characteristics and Classification of Arthropoda

Arthropoda is the largest phylum in the animal kingdom. the phylum  includes about 805 of the known animal species.. The phylum includes prawns, crabs, lobsters, cockroaches, scorpions, spiders, ticks, insects etc. Arthropods  are economically  of great importance to man. Animals like honey bees, silkworm moth etc, are beneficial. 

General Characters of Phylum Arthropoda
1. Arthropods are bilaterally symmetrical and triploblastic.
2. The body bears paired, jointed appendages and they are variously modified for different functions.
3. The body is covered with a thick chitinous cuticle forming an exoskeleton which is shed at regular intervals.
4. Compund eyes are present in most of the members
5. Respiration is by gills or book lungs or trachea
6. Excretion is by green glands or malpigian tubules.
7. Open circulatory system
8. The body is composed of many segments
Classification of Arthropoda

Classification of Phlum Arthropoda
The phylum  is divided into different classes namely: Crustacea, Arachnids, Myriapods and Insects (BE4U Tips: CAMI)

  • Crusta means hard shell
  • More than 4 pairs of jointed legs
  • Example: Prawns, Crabs, Lobsters

spider and web

  • Body divided into head cephalothorax
  • 4 pairs of jointed legs
  • Example of Arachids: Spider, Scorpion, Limulus, Ticks and mites

Myriapods :
Centipedes and Millipedes

  • Many similar segments, each with at least one pair of jointed legs
  • Example of Myriapods : Centipedes and Millipedes


  • Body  divided into head, thorax and abdomen,
  • 6 jointed legs attached to the thorax
  • 4 wings attached to the thorax
  • Example of insects: Cockroach, butterflies, grass hopper 
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Classification of Living Things: 5 Vertebrate Groups

The animal kingdom includes vertebrates and arthropods. Vertebrates are animals with backbones, i.e., they have a vertebral column. The subphylum  vertebrata comprises the major part of phylum chordata which includes mammals, reptiles, fishes, amphibians, birds.

BE4U tips: MR FAB (Mammals, Reptiles, Fishes, Amphibians, Birds)

  •        Hair
  •         Four chambered heart
  •         Placenta,
  •         Mammary gland
  •         Different types of teeth
  •         Presence of epidermal scales, which are modified in some to form shields or plates
  •         Lay soft shelled eggs on land
Fish (Pisces):
  •        Streamlined body
  •        Presence of scales
  •        Paired fins
  •        Lay eggs with no shells in water
  •         Presence of smooth skin
  •         Heart is three chambered
  •         Lay eggs with no shells in water
Birds (Aves):
  •        Presence of feathers, wings, beak
  •        4 chambered heart
  •        Lay eggs with hard shells
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IGCSE Biology Notes - The Taxonomic Hierarchy - Human Hierarchy

Once you named an organism you have to assign an appropriate position in a systematic frame work of classification. This frame work is called taxonomic hierarchy by which the taxonomic groups are arranged in a definite order from higher to lower categories. Each category in the hierarchy is considered as a taxonomic unit and is known as taxon.
Taxonomic Hierarchy
  • The categories used in the classification of animals are 
                               Kingdom, Phylum, Class, Order, Family, Genus , Species. 
  • BE4U TIPS :     King      Philip     Came  Over    For      Good    Spinach
  •  These categories are ranked on above the other, called Hierarchy.
  • Kingdom is the highest and species is the lowest category in this hierarchy.
Taxonomic Hierarchy of Animals
Example : Human (Scientific name: Homo sapiens)
Taxonomic position of Human                                                         
Kingdom - Animalia
Phylum- Chordata
Class- Mammalia
Order - Primates
Family- Hominidae
Genus- Homo
Species- sapiens 
Taxonomic hierarchy (human taxonomy chart)

Taxonomic Hierarchy in Plants

  •  In the case of plants instead of phylum, division is used. 
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