Category: A-level Biology

Explain why measles vaccine administered at the age of 9 month

09/02/2023 1

It was estimated that weaning on average occurs at this age, and the baby no longer gets antibodies against measles from the mothers. Read More

Explain why sickle cell trait is prevalent in malaria prone areas

04/27/2023 1

Sickle cell trait is caused by a recessive allele in heterozygote state. Malaria acts as a selection pressure for heterozygote promoting their high occurrence in ... Read More

When light and temperature are optimum while carbon dioxide concentration is low, the rate of photosynthesis can’t increase further.

04/27/2023 0

In isolated populations mutations and natural selection occurs differentially leading to evolution of new species Read More

Structure of the earth, continental drift and earthquakes

04/27/2023 0

Physical geography Chapter 1: Structure of the earth, continental drift and earthquakes In the universe we live on planet earth, is the third planet from the ... Read More

Explain the effects of the heterozygote advantage in a population with increasing gene

11/09/2022 7

Increasing gene flow reduces the probability of recessive alleles   or disadvantageous alleles in the population as it introduces new alleles. This reduced the selection pressure ... Read More

State four physiological differences between C3 and C4 plants.

10/28/2022 0

Difference between C3, and C4 plant C3 pathway C4 pathway 1 Photosynthesis occurs in mesophyll cells Photosynthesis occurs in mesophyll cells and bundle sheath cells ... Read More

Explain how light influences stomatal opening in a plant that has been previously in the dark.

10/28/2022 0

When exposed to light, starch of the guard cells is converted into malic acid, Malic acid dissociate into malate and H+ ions in the guard ... Read More

Does milk contain iron?

10/28/2022 0

Dairy products such as cheese, cottage cheese, milk and yogurt, although rich in calcium, have negligible iron content Read More

What part is played by the mammalian skin in excretion?

10/27/2022 0

Sweating eliminates urea, a by-product of protein catabolism, excess water and salts Read More

What is the role of stored proteins during seed germination

10/27/2022 0

Provide a source of amino acids and reduced N necessary for synthesis  of enzymes, and for formation of structures in developing embryo. some may be ... Read More

Methods to reduce soils erosion are

10/25/2022 1

Afforestation Planting grass cover Mulching Strip cropping Terracing Contour cropping Read More

Types of soil erosion

10/25/2022 2

Sheet erosion: the surface of the soil is removed evenly over the whole surface of a slope Rill erosion: top soil is removed to an ... Read More

Effects of adrenaline in the body.

10/25/2022 2

increase rate of heart beat increases rate of breathing increases metabolic rate increase blood pressure and increases blood flow to brain and muscle enlarges pupil ... Read More

What’s the difference between endocrine and exocrine glands?

10/25/2022 1

Exocrine glands secrete their substances through ducts onto your body's surfaces. On the other hand, endocrine glands secrete their substances directly into your bloodstream Read More

Name the constituents of the mammalian blood

10/24/2022 0

plasma, red blood cells, white blood cells, and platelets, water, food nutrients (glucose, amino acids, fatty acids, vitamins), waste products (like urea and ammonia) hormones, ... Read More

How does clay affect the fertility of soil?

10/24/2022 0

Contain plant nutrients Increases soil capillarity Increase soil water retention Provide firm anchorage to the plants Read More

Explain the value/importance of earthworms in maintaining a condition suitable for crop growing.

10/24/2022 0

. Tunnels improve aeration and drainage of soil causes decay and formation of humus source of food to other animals e.g. chicken die and rot ... Read More

Describe an experiment to demonstrate hydrotropism in plant roots and shoots.

10/24/2022 0

Hydrotropism: 1. Hydrotropic movements refer to a plant's movement or growth in response to a water stimulus, while hydrotropism refers to the analogous response to ... Read More

Benefits of studying genetics

10/24/2022 0

helps researchers develop new strategies to treat and prevent human disease. Help to understand more about the genetic basis of human diseases. Genetic engineering such ... Read More

Distinguish between dominant and recessive genes

10/24/2022 0

A dominant gene is the one that expresses itself entirely in heterozygous state while a recessive gene is one masked in heterozygous state Read More

Distinguish between phenotype and genotype

10/24/2022 0

Phenotype is the physical characteristic of an organism determined by the genotype and the environment. Genotype is the genetic constitution of an organism i.e. the ... Read More

Adaptations of fish for locomotion/swimming

10/24/2022 0

Streamline shape reduces friction Eye to see in water Pectoral, pelvic and ventral fins for balancing. Slippery body reduce friction Has gills to extract oxygen ... Read More

What is a multiple allele?

10/22/2022 0

The presence of three or more alleles for a given gene is referred to as multiple alleles. Read More

What are sex-linked genes?

10/22/2022 0

Sex linked genes are those that sit on sex chromosomes and that are inherited differently in males and females Read More

What is codominance

10/22/2022 0

Codominance, in genetics, phenomenon in which two alleles (different versions of the same gene) are expressed to an equal degree within an organism. Read More

What does heterozygote mean?

10/22/2022 20

Heterozygous refers to having different alleles for a particular trait Read More

What happens when onion epidermis is placed in strong sugar solution

10/22/2022 0

The cells of the epidermis placed in strong sugar solution lost water by osmosis, and became flaccid Read More

What happens when onion epidermis is placed in water

10/22/2022 0

The cells of the epidermis placed in pure water gained water by osmosis, swell and became turgid Read More

When mucus fills the Eustachian tube, hearing is impaired. Explain why.

10/22/2022 0

It may causes increase in pressure in the middle air which distorts vibration of the eardrum and ossicles Read More

How does the blockade of Eustachian tube affect hearing?

10/22/2022 0

Obstruction or blockage of the Eustachian tube results in a negative middle ear pressure, which will cause the ear drum to retract (suck in). In ... Read More

What is the function of hair and wax in ear canal

10/22/2022 0

Wax  and protects the ear from invasion of organisms and keeps away dirt and debris from the ear drum Read More

Adaptations of insect pollinated flowers and wind pollinated flowers

10/21/2022 0

Note that there is a difference between characteristics and adaptations of flowers Adaptations of Insects pollinated flowers brightly colored petals to attract pollinators scented to ... Read More

The importance of a skeleton to an organism

10/21/2022 0

 Hydrostatic skeleton provides support form movement Exoskeleton1.It minimize water loss by evaporation 2.It protects the internal soft tissue 3.It determine maximum size of the organism ... Read More

Types of skeletons

10/21/2022 0

There are three types of skeleton Hydrostatic skeleton Here support is provided by a fluid under pressure and it is found in round worms, earthworm. ... Read More

Parts of motor neuron/nerve

10/21/2022 0

Functions of parts of nerve cell Nerve fibre or axon transmits impulses The myelin sheath protects the axon; it also insulates the axon and speeds ... Read More

Functions of parts of nerve cell

10/21/2022 0

Nerve fibre or axon transmits impulses The myelin sheath protects the axon; it also insulates the axon and speeds up transmission of impulse. Nucleus controls ... Read More

What happens to old red blood cells in the body?

10/20/2022 1

Old or damaged RBCs are removed from the circulation by macrophages in the spleen and liver, and the hemoglobin they contain is broken down into heme ... Read More

A-level math paper 1 Inequalities

10/19/2022 0

Please double click and download the PDF below A-level math paper 1 Inequalities Read More

Adaptations of a bony fish to movement in water

10/17/2022 25

- has streamline shape to reduce drag force - has tail fin for propulsion - has fins for stability - has slippery body  to reduce ... Read More

Differences between bones and cartilages

10/17/2022 0

  Differences between bones and cartilages   Bones Cartilages 1 Bone is tough and hard Cartilage is soft and flexible 2 Bones cannot bend Cartilages ... Read More

Pentadactyl limb

10/16/2022 0

It is so called because typically has five digits, is found in all four classes of terrestrial vertebrate some of the limbs bone can even ... Read More

The largest section of the human brain is the …

10/16/2022 0

Cerebrum. The cerebrum (front of brain) comprises gray matter (the cerebral cortex) and white matter at its center. The largest part of the brain, the ... Read More

Describe how the various parts of the human digestive system are adapted to their functions

10/15/2022 0

Adaptations of the mouth for digestion Contains space to receive food by ingestion, contains teeth to break food into small particles by mastication contains saliva to ... Read More

Describe the process of fertilization in human beings.

10/15/2022 1

Fertilization occurs when a sperm fuses with Ovum; during intercourse sperms are released from the testis through the urethra  into the vagina. The sperm travels through ... Read More

Adaptations of schistosoma mansoni to the parasitic mode of life

10/15/2022 0

has  cilia or tails for swimming to find the host has secretory glands for host penetration, has a tegument and glycocalyx for parasite protection/host immuno-modulation, has ... Read More

What is chistosoma mansoni?

10/15/2022 0

Schistosoma mansoni is a water-borne parasite of humans transmitted by water snail, and belongs to the group of blood flukes. The adult lives in the ... Read More

What is parasitism?

10/15/2022 0

Parasitism is a relationship between two species of plants or animals in which one lives in or on another organism benefits at the expense of ... Read More

To which bones is the biceps muscle attached by tendons?

10/14/2022 0

Finally, the short head of the biceps brachii, due to its attachment to the scapula (or shoulder blade), assists with stabilization of the shoulder joint when a ... Read More

What is thigmotropism?

10/14/2022 0

Thigmotropism is a directional growth movement which occurs as a mechanosensory response to a touch stimulus. Thigmotropism is typically found in twining plants and tendrils, however ... Read More

What is a plant body called that has not differentiated into roots stems and leaves?

10/14/2022 0

Thallophytes are any group of organisms, including algae, fungi, and lichens, that show no differentiation into stem, root, or leaf and were formerly regarded as constituting ... Read More

What is an axial skeleton?

10/14/2022 23

Your axial skeleton is made up of the bones in your head, neck, back and chest. Your appendicular skeleton is made up of everything else — ... Read More

Give the importance to the plants of each of the components that make up a fertile soil.

10/13/2022 0

Soil components and their uses Soil component Use Air Oxygen is particularly required for respiration of micro organism and plant roots; decomposition of organic matter, ... Read More

An experiment to show that germinating seeds liberate carbon dioxide.

10/12/2022 0

Set up Air is drawn over the germinating seeds using a suction pump for some time. Observation Lime water in conical flask D turns milk ... Read More

Testing for presence of starch in leaves

10/12/2022 0

The leaf is boiled in hot water to kill the protoplasm The boiled leaf is placed in boiling alcohol to remove chlorophyll The leaf without ... Read More

Suggest the main functions and deficiency symptoms of nitrogen, magnesium and phosphorus to the plant

10/11/2022 0

  ELEMENT FUNCTION EFFECT OF DEFICIENCY Nitrogen   Nitrogen is required by plants to produce amino acids, proteins, and DNA. Nitrogen is necessary because it is ... Read More