Temperature has direct effect on which of the following?
i. body size
ii. size of the extremities of the body
iii. Mutation
iv. life span
v. metabolism in poikilotherm

Options

A. i, iii, and iv
B. ii, iii and iv
C. ii, iii and v
D. i, ii and v

Answer

To determine the direct effects of temperature on the given options, we can analyze each one:

1. **Body Size**: Temperature can influence body size in various organisms. For example, in colder climates, animals may develop larger body sizes as a response to the need for heat retention (Bergmann's Rule). Thus, temperature has a direct effect on body size.

2. **Size of Extremities of the Body**: Extremities such as ears and limbs can also be affected by temperature. In warmer climates, animals may have longer extremities to help dissipate heat (Allen's Rule). Therefore, temperature directly affects the size of extremities.

3. **Mutation**: While temperature can influence mutation rates indirectly by affecting the environment and stress levels, it does not have a direct effect on the mutation itself. Mutations occur randomly and are not directly caused by temperature changes.

4. **Life Span**: Temperature can affect the life span of organisms. For instance, higher temperatures can lead to increased metabolic rates, which may shorten life spans in some species. Thus, temperature has a direct effect on life span.

5. **Metabolism in Poikilotherms**: Poikilothermic organisms (cold-blooded animals) have metabolic rates that are directly influenced by temperature. As the temperature increases, so does their metabolism. Therefore, temperature has a direct effect on metabolism in poikilotherms.

Based on this analysis, the options that temperature has a direct effect on are:
- Body size
- Size of the extremities of the body
- Life span
- Metabolism in poikilotherms

**Final Answer**: i. Body size, ii. Size of the extremities of the body, iv. Life span, v. Metabolism in poikilotherms.