WAEC SSCE - Biology - 1988
Question 1 Report
THe bicuspid valve is located between the
Answer Details
The bicuspid valve, also known as the mitral valve, is located between the left auricle (the upper chamber on the left side of the heart) and the left ventricle (the lower chamber on the left side of the heart). It allows blood to flow from the left atrium into the left ventricle, but prevents blood from flowing back into the atrium when the ventricle contracts and pumps blood out to the body.
Question 2 Report
Auxins are produced in the
Answer Details
Auxins are a type of plant hormone that play a crucial role in growth and development. They are primarily produced in the apical regions of both roots and shoots. These regions are responsible for the growth of the plant, so the production of auxins in these areas allows for the regulation of growth and development throughout the plant. While auxins can also be found in other parts of the plant such as the parenchyma of roots and shoots, and the epidermis of roots and shoots, their primary site of production is in the apical regions.
Question 3 Report
The pituitary is called 'master gland' because
Answer Details
The pituitary gland is called the 'master gland' because it controls the functions of many other glands in the body. It does this by producing and secreting hormones that stimulate or inhibit the production of hormones from other glands. So, it acts as a central regulator of the endocrine system, which is responsible for maintaining the body's internal balance and regulating various physiological processes. Additionally, the pituitary gland is located in the brain and is connected to the hypothalamus, which is a key region that controls many essential bodily functions such as hunger, thirst, and temperature regulation.
Question 4 Report
Which of the following statements is not true of a climax vegetation? It
Answer Details
The statement that is not true of a climax vegetation is that it eliminates competition. Climax vegetation is a stable community of plants and animals that has reached a state of equilibrium and is able to persist over time under prevailing environmental conditions. However, competition between different species in the community can still occur, although it may be reduced compared to earlier stages of succession. The development of climax vegetation is the result of a process called succession, in which different plant and animal communities replace one another over time until a stable, diverse community is established. The colonization of a habitat by plants and animals is a key aspect of this process.
Question 5 Report
Which of the following best describes the homologous chromosomes? They are
Question 6 Report
Even though some flowering plants contain accessory pigments which give them colours they still contain
the pigment
Answer Details
Flowering plants primarily contain chlorophyll pigments, which are responsible for their green coloration and essential for photosynthesis. However, some plants also contain accessory pigments such as carotenoids, xanthophylls, and anthocyanins, which give them additional colors such as yellow, orange, and red. So, even though some flowering plants contain these accessory pigments, they still contain chlorophyll pigment. In fact, the presence of these accessory pigments doesn't affect the presence of chlorophyll in plants; instead, they complement and enhance their visual appeal.
Question 7 Report
The relationship between a herbivore and the bacteria which live in its caecum is known as
Answer Details
The relationship between a herbivore and the bacteria that live in its caecum is known as "symbiosis." Symbiosis is a close and long-term interaction between two different species, where both species benefit from the relationship. In this case, the herbivore provides a warm and nutrient-rich environment in its caecum for the bacteria to live in, and the bacteria help the herbivore digest tough plant material, breaking down cellulose into simpler compounds that the herbivore can absorb as nutrients. This mutualistic relationship benefits both the herbivore and the bacteria, and they depend on each other for survival.
Question 8 Report
The brain and the spinal cord make up the
Answer Details
The brain and the spinal cord make up the central nervous system (CNS). The CNS is responsible for processing and coordinating information from the senses, controlling movements, and regulating body functions. It receives information from the peripheral nervous system (PNS), which consists of the nerves that extend from the CNS to the rest of the body. The CNS is responsible for many of the body's important functions, including consciousness, thought, memory, and emotion.
Question 9 Report
Which of the following blood components has the greatest affinity for oxygen and carbondioxide?
Answer Details
Erythrocytes, also known as red blood cells, have the greatest affinity for oxygen and carbon dioxide. This is because they contain a protein called hemoglobin, which binds to oxygen and carbon dioxide and transports them throughout the body. Hemoglobin has a high affinity for oxygen, which allows it to pick up oxygen in the lungs and deliver it to tissues throughout the body that need it. Hemoglobin also has a moderate affinity for carbon dioxide, which allows it to pick up carbon dioxide from tissues and transport it back to the lungs to be exhaled. Therefore, erythrocytes are essential for maintaining proper oxygen and carbon dioxide levels in the body.
Question 10 Report
If a cross is made between a pure-breeding red flowered plant and a pure-breeding white flowered plant
where R is dominant for red flower and r is recessive for white, the most likely result of F generation will be
Answer Details
Question 11 Report
Co-ordination is achieved in the body of mammals through the action of the
Answer Details
Coordination in the body of mammals is primarily achieved through the action of the endocrine and nervous systems working together. The nervous system consists of the brain, spinal cord, and nerves that transmit electrical impulses, while the endocrine system consists of glands that produce hormones that travel through the bloodstream to target organs and tissues. Together, these systems regulate and control bodily functions such as movement, sensation, digestion, and metabolism, ensuring that all parts of the body work together in harmony. While the skeletal, muscular, and circulatory systems are also important for movement and support, they do not play as significant a role in overall coordination as the endocrine and nervous systems.
Question 12 Report
During blood transfusion, agglutination may occur as a result of the reaction between
Answer Details
Question 13 Report
A man with blood group A (TAP) married a woman with blood group O (pp). Which of the following is the
probable ratio of the blood groups of the offspring?
Answer Details
Question 14 Report
Double fertilization is said to occur in flowering pants because
Answer Details
Double fertilization is a unique process that occurs in flowering plants during sexual reproduction. In this process, two sperm cells from a single pollen grain fertilize two different nuclei in the female reproductive structure of the flower. The first sperm fertilizes the egg cell, forming a zygote, which eventually develops into an embryo. The second sperm fuses with the polar nuclei, which results in the formation of the endosperm. The endosperm is a food-rich tissue that provides nourishment to the developing embryo. So, the correct option is "one embryo and endosperm nucleus are formed." Double fertilization leads to the formation of both an embryo and the endosperm, which provides nutrients for the developing embryo to grow into a mature seed.
Question 15 Report
The vector of the malarial parasite is the
Answer Details
The vector of the malarial parasite is the female Anopheles mosquito. This is because female Anopheles mosquitoes feed on the blood of humans and animals, and when they bite an infected person, they can transmit the malaria parasite from that person's blood to their own. The parasite then multiplies inside the mosquito, and when the mosquito bites another person, it can transmit the parasite to them, thus spreading the disease. It is important to note that male mosquitoes do not feed on blood, and therefore cannot transmit the malaria parasite.
Question 16 Report
The change in colour of the chameleon serves as a means of
Answer Details
The change in color of the chameleon serves as a means of camouflage from predators. Chameleons have the unique ability to change the color of their skin to blend in with their surroundings. This helps them avoid being detected by predators and increases their chances of survival. The color change is achieved through the manipulation of pigments in the skin cells called chromatophores, which expand or contract to reveal different colors. Therefore, the color change is not for attracting a mate, repelling enemies, regulating body temperature, or producing a variety of skin pigments, but rather for camouflage purposes.
Question 19 Report
Which of the following is not regarded as a micro-nutrient or trace element for plant growth?
Answer Details
Question 20 Report
The haploid number of chromosomes in man is
Answer Details
The haploid number of chromosomes in humans is 23. Haploid refers to the number of chromosomes in a cell that contains only one set of chromosomes. In humans, the cells that are haploid are the sperm and egg cells. Each human cell normally contains 46 chromosomes, which are arranged in 23 pairs. When a sperm cell fertilizes an egg cell, the resulting zygote (fertilized egg) contains 23 pairs of chromosomes, or a total of 46 chromosomes. During the process of meiosis, which occurs in the cells that produce sperm and egg cells, the number of chromosomes is reduced from 46 to 23. This is because the cells divide twice, but the chromosomes only replicate once. As a result, each of the four resulting cells has only 23 chromosomes, which is the haploid number for humans.
Question 21 Report
Which of the following is not true about gene mutation? It
Answer Details
The statement that is not true about gene mutation is that it always affects the chromosome number. Gene mutation refers to any change that occurs in the DNA sequence of a gene, and it can result in different outcomes. For instance, gene mutation can introduce new traits into a population by altering the sequence of nucleotides in a gene, which can lead to changes in the phenotype (observable traits). However, some mutations may have an unnoticeable effect on the phenotype, and the individual carrying the mutation may appear normal. Gene mutations do not always affect the chromosome number, and there are two types of mutations that affect the chromosome number, which are called chromosomal mutations. These mutations involve changes in the structure or number of chromosomes, and they can lead to genetic disorders or conditions such as Down syndrome. In summary, gene mutation can introduce new traits into a population, cause changes in the DNA, have unnoticeable effects on the phenotype, and be a source of new genes. However, gene mutation does not always affect the chromosome number.
Question 24 Report