The two important features of sexual reproduction in higher organisms that create genetic diversity in offspring are
- A.Mitosis and fertilization
- B.Meiosis and fertilization
- C.Mitosis and binary fission
- D.Meiosis and conjugation
Correct answer
Explanation
The correct answer is B, Meiosis and fertilization. Meiosis makes gametes that differ from one another, and fertilization joins a gamete from each of two parents, so every offspring gets a new mix of genes.
Meiosis is the reduction division that halves the chromosome number, from diploid (2n) to haploid (n), when sperm and eggs form. During it, crossing over swaps segments between paired chromosomes, and independent assortment shuffles which chromosome of each pair goes into a gamete. Fertilization then fuses two such gametes at random and restores the diploid number. Together the two steps keep the chromosome number constant across generations while making each offspring genetically unique.
A is wrong because mitosis produces cells identical to the parent cell and adds no variation.
C is wrong because mitosis and binary fission are both part of asexual reproduction or growth, and they make copies.
D is wrong because conjugation is a way of exchanging genetic material in bacteria and Paramecium, not part of sexual reproduction in higher organisms.
Exam tip: mitosis, growth and identical cells; meiosis, gametes and variation.
Practice Questions
View allWhich one of the following is the 'energy currency' for cellular processes?
- A.Glucose
- B.ATP
- C.ADP
- D.Pyruvic acid
Show answer
Adenosine triphosphate stores energy in its phosphate bonds and releases it wherever the cell needs it, so it is called the energy currency of the cell.
Read the full explanation →Which one of the following is the correct reactivity order of metals reacting with dilute HCl?
- A.Mg > Al > Zn > Fe
- B.Mg < Al < Zn < Fe
- C.Mg > Zn > Fe > Al
- D.Fe > Mg > Al > Zn
Show answer
This is the order in which these metals stand in the reactivity series, and it matches how vigorously they release hydrogen from dilute hydrochloric acid.
Read the full explanation →Deficiency of iron causes
- A.Anaemia
- B.Scurvy
- C.Rickets
- D.Cholera
Show answer
Iron is needed to make haemoglobin, so too little iron means too little haemoglobin and a reduced ability of the blood to carry oxygen.
Read the full explanation →Consider the following statements regarding waves : 1. If the particles of a medium move along the direction of motion of the wave, the wave is called a longitudinal wave. 2. If the particles of a medium move perpendicular to the direction of motion of the wave, the wave is called a transverse wave. 3. Transverse waves may involve change in the shape of the medium, whereas longitudinal waves involve change in the density of the medium. Which of the statements given above is/are correct ?
- A.1 and 2 only
- B.1 only
- C.2 and 3 only
- D.1, 2 and 3
Show answer
All three statements correctly describe how particles move in the two kinds of mechanical waves. In a longitudinal wave, such as sound in air, the particles vibrate back and forth along the direction in which the wave travels.
Read the full explanation →In paper manufacturing, degumming of the raw material is done using
- A.sulphuric acid
- B.bleaching powder
- C.caustic soda
- D.nitric acid
Show answer
In paper making the raw plant material is cooked with caustic soda, which dissolves the gums, resins and lignin that bind the cellulose fibres together.
Read the full explanation →