Give an example of characteristics being used to determine how close two species are in evolutionary terms.
The more characteristics of two species have in common, they seem to be more closely related. And the more closely they are related, more recently they shared a common ancestor or the evolutionary relationship.
Mostly the homologous characteristics derive from how close two species are in evolutionary terms. For example, mammals have four limbs as birds, reptiles and amphibians possess. Basic structures of the limbs are very similar and they are modified to do different functions. The characteristics can be similar in different organisms because of sharing the common ancestors which helps to identify the evolutionary relationship among two close related species. Another example is the common connection link between the reptiles and birds. The connecting link between the reptiles and the birds are known as archaeopteryx. Aves have the evolutionary characters which are derived from the reptiles, in which the forelimbs of the reptiles modified into the feathers or the wings.
Outline a project which aims to find the dominant coat colour in dogs.
How is the sex of the child determined in human beings?
A man with blood group A marries a woman with blood group O and their daughter has blood group O. Is this information enough to tell you which of the traits – blood group A or O – is dominant? Why or why not?
How do Mendel’s experiments show that traits are inherited independently?
If a trait A exists in 10% of a population of an asexually reproducing species and a trait B exists in 60% of the same population, which trait is likely to have arisen earlier?
Explain how sexual reproduction gives rise to more viable variations than asexual reproduction. How does this affect the evolution of those organisms that reproduce sexually?
Explain the terms analogous and homologous organs with examples.
How do Mendel’s experiments show that traits may be dominant or recessive?
How does the creation of variations in a species promote survival?
Will geographical isolation be a major factor in the speciation of an organism that reproduces asexually? Why or why not?
Did Döbereiner’s triads also exist in the columns of Newlands’ Octaves? Compare and find out.
What is a good source of energy?
Why is diffusion insufficient to meet the oxygen requirements of multi-cellular organisms like humans?
What are trophic levels? Give an example of a food chain and state the different trophic levels in it.
What changes can you make in your habits to become more environment-friendly?
What is the difference between a reflex action and walking?
What is the importance of DNA copying in reproduction?
Why should a magnesium ribbon be cleared before burning in air?
Define the principal focus of a concave mirror.
You have been provided with three test tubes. One of them contains distilled water and the other two contain an acidic solution and a basic solution, respectively. If you are given only red litmus paper, how will you identify the contents of each test tube?
What are the qualities of an ideal source of energy?
Why does the sky appear dark instead of blue to an astronaut?
Compare the power used in the 2 Ω resistor in each of the following circuits:
(i) a 6 V battery in series with 1 Ω and 2 Ω resistors, and (ii) a 4 V battery in parallel with 12 Ω and 2 Ω resistors.
The refractive index of diamond is 2.42. What is the meaning of this statement?
Write the balanced equation for the following chemical reactions.
1. Hydrogen + Chlorine → Hydrogen chloride
2. Barium chloride + Aluminium sulphate → Barium sulphate + Aluminium chloride
3. Sodium + Water → Sodium hydroxide + Hydrogen
10 mL of a solution of NaOH is found to be completely neutralised by 8 mL of a given solution of HCl. If we take 20 mL of the same solution of NaOH, the amount HCl solution (the same solution as before) required to neutralise it will be
(a) 4 mL (b) 8 mL (c) 12 mL (d) 16 mL
Which uses more energy, a 250 W TV set in 1 hr, or a 1200 W toaster in 10 minutes?
What are the differences between autotrophic nutrition and heterotrophic nutrition?
The autotrophic mode of nutrition requires
(a) carbon dioxide and water. (c) sunlight.
(b) chlorophyll. (d) all of the above.
Why is variation beneficial to the species but not necessarily for the individual?